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SEC Schedule, Article 12-28, Real Estate and Accumulated Depreciation (Details) - USD ($) | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2025 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances | [1] | $ 4,280,067,000 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 5,656,418,000 |  |  |  |
Original Building |  | 15,510,064,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 7,719,548,000 |  |  |  |
Land and Improvements | [2] | 5,918,915,000 |  |  |  |
Building and Improvements | [3] | 20,973,366,000 |  |  |  |
Land held for development | [5] | 518,492,000 | [4] | $ 714,050,000 |  |
Development and Construction in Progress |  | 1,475,257,000 |  | 764,640,000 |  |
Total |  | 28,886,030,000 |  | 28,521,176,000 | $ 27,421,471,000 | $ 25,744,214,000
Accumulated Depreciation |  | 8,003,414,000 |  | 7,485,502,000 | 6,841,404,000 | 6,260,992,000
Furniture, Fixtures and Equipment |  | 54,160,000 |  | 57,136,000 |  |
Aggregate cost for tax purpose |  | 26,700,000,000 |  |  |  |
Real Estate Aggregate Accumulated Depreciation For Tax Purposes |  | 6,800,000,000 |  |  |  |
Debt Issuance Costs, Net |  | (18,000,000.0) |  |  |  |
Right-of-use assets - finance leases |  | 372,470,000 |  | 372,922,000 |  |
Right of use assets - operating leases |  | $ 325,841,000 |  | 334,767,000 |  |
Maximum [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Real Estate and Accumulated Depreciation, Life Used for Depreciation |  | 40 years |  |  |  |
Furniture, fixtures, and equipment |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Accumulated Depreciation Related to Furniture, Fixtures and Equipment |  | $ 36,897,000 |  |  |  |
Land and Land Improvements [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Right-of-use assets - finance leases |  | 349,314,000 |  |  |  |
Right of use assets - operating leases |  | 325,841,000 |  |  |  |
Buildings and improvements |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Right-of-use assets - finance leases |  | 23,156,000 |  |  |  |
767Fifth Avenue (the General Motors Building) | Office Building [Member] |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances |  | 2,294,992,000 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 1,796,252,000 |  |  |  |
Original Building |  | 1,532,654,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 423,940,000 |  |  |  |
Land and Improvements |  | 1,796,247,000 |  |  |  |
Building and Improvements |  | 1,956,599,000 |  |  |  |
Total |  | 3,752,846,000 |  |  |  |
Accumulated Depreciation |  | $ 614,923,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Prudential Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 92,077,000 |  |  |  |
Original Building |  | 948,357,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 862,028,000 |  |  |  |
Land and Improvements |  | 115,639,000 |  |  |  |
Building and Improvements |  | 1,786,823,000 |  |  |  |
Total |  | 1,902,462,000 |  |  |  |
Accumulated Depreciation |  | $ 871,069,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Embarcadero Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 179,697,000 |  |  |  |
Original Building |  | 847,410,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 597,249,000 |  |  |  |
Land and Improvements |  | 195,986,000 |  |  |  |
Building and Improvements |  | 1,428,370,000 |  |  |  |
Total |  | 1,624,356,000 |  |  |  |
Accumulated Depreciation |  | $ 873,659,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
399 Park Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 339,200,000 |  |  |  |
Original Building |  | 700,358,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 431,612,000 |  |  |  |
Land and Improvements |  | 354,107,000 |  |  |  |
Building and Improvements |  | 1,117,063,000 |  |  |  |
Total |  | 1,471,170,000 |  |  |  |
Accumulated Depreciation |  | $ 564,004,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
601 Lexington Avenue | Office Building [Member] |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances |  | $ 991,878,000 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 241,600,000 |  |  |  |
Original Building |  | 494,782,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 569,220,000 |  |  |  |
Land and Improvements |  | 289,639,000 |  |  |  |
Building and Improvements |  | 1,015,963,000 |  |  |  |
Total |  | 1,305,602,000 |  |  |  |
Accumulated Depreciation |  | $ 429,085,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
200 Clarendon Street and Garage | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 219,543,000 |  |  |  |
Original Building |  | 667,884,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 311,929,000 |  |  |  |
Land and Improvements |  | 258,001,000 |  |  |  |
Building and Improvements |  | 941,355,000 |  |  |  |
Total |  | 1,199,356,000 |  |  |  |
Accumulated Depreciation |  | $ 392,736,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Salesforce Tower | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 200,349,000 |  |  |  |
Original Building |  | 946,205,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 4,149,000 |  |  |  |
Land and Improvements |  | 200,349,000 |  |  |  |
Building and Improvements |  | 950,354,000 |  |  |  |
Total |  | 1,150,703,000 |  |  |  |
Accumulated Depreciation |  | $ 214,753,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
250 West 55th Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 285,263,000 |  |  |  |
Original Building |  | 603,167,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 49,995,000 |  |  |  |
Land and Improvements |  | 285,263,000 |  |  |  |
Building and Improvements |  | 653,162,000 |  |  |  |
Total |  | 938,425,000 |  |  |  |
Accumulated Depreciation |  | $ 232,085,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
100 Federal Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 131,067,000 |  |  |  |
Original Building |  | 435,954,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 154,169,000 |  |  |  |
Land and Improvements |  | 131,067,000 |  |  |  |
Building and Improvements |  | 590,123,000 |  |  |  |
Total |  | 721,190,000 |  |  |  |
Accumulated Depreciation |  | $ 209,057,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
7 Times Square | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 165,413,000 |  |  |  |
Original Building |  | 380,438,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 159,914,000 |  |  |  |
Land and Improvements |  | 169,193,000 |  |  |  |
Building and Improvements |  | 536,572,000 |  |  |  |
Total |  | 705,765,000 |  |  |  |
Accumulated Depreciation |  | $ 279,693,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Madison Centre | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 104,641,000 |  |  |  |
Original Building |  | 564,336,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 5,672,000 |  |  |  |
Land and Improvements |  | 104,641,000 |  |  |  |
Building and Improvements |  | 570,008,000 |  |  |  |
Total |  | 674,649,000 |  |  |  |
Accumulated Depreciation |  | $ 76,377,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Santa Monica Business Park [Member] | Office Building [Member] |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances |  | $ 199,302,000 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 46,360,000 |  |  |  |
Original Building |  | 410,421,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 217,684,000 |  |  |  |
Land and Improvements |  | 210,471,000 |  |  |  |
Building and Improvements |  | 462,459,000 |  |  |  |
Land held for development |  | 1,535,000 |  |  |  |
Total |  | 674,465,000 |  |  |  |
Accumulated Depreciation |  | $ 36,680,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Carnegie Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 142,666,000 |  |  |  |
Original Building |  | 316,856,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 194,968,000 |  |  |  |
Land and Improvements |  | 94,243,000 |  |  |  |
Building and Improvements |  | 501,021,000 |  |  |  |
Land held for development |  | 59,226,000 |  |  |  |
Total |  | 654,490,000 |  |  |  |
Accumulated Depreciation |  | $ 294,418,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Reston Next | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 35,549,000 |  |  |  |
Original Building |  | 525,277,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 17,150,000 |  |  |  |
Land and Improvements |  | 2,901,000 |  |  |  |
Building and Improvements |  | 575,075,000 |  |  |  |
Total |  | 577,976,000 |  |  |  |
Accumulated Depreciation |  | $ 69,776,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Atlantic Wharf | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 63,988,000 |  |  |  |
Original Building |  | 454,537,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 45,916,000 |  |  |  |
Land and Improvements |  | 63,988,000 |  |  |  |
Building and Improvements |  | 500,453,000 |  |  |  |
Total |  | 564,441,000 |  |  |  |
Accumulated Depreciation |  | $ 210,601,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
2100 Pennsylvania Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 185,203,000 |  |  |  |
Original Building |  | 324,206,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 5,228,000 |  |  |  |
Land and Improvements |  | 185,203,000 |  |  |  |
Building and Improvements |  | 329,434,000 |  |  |  |
Total |  | 514,637,000 |  |  |  |
Accumulated Depreciation |  | $ 48,475,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
599 Lexington Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 81,040,000 |  |  |  |
Original Building |  | 100,507,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 285,903,000 |  |  |  |
Land and Improvements |  | 87,852,000 |  |  |  |
Building and Improvements |  | 379,598,000 |  |  |  |
Total |  | 467,450,000 |  |  |  |
Accumulated Depreciation |  | $ 218,359,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Fountain Square | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 56,853,000 |  |  |  |
Original Building |  | 306,298,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 60,266,000 |  |  |  |
Land and Improvements |  | 56,853,000 |  |  |  |
Building and Improvements |  | 366,564,000 |  |  |  |
Total |  | 423,417,000 |  |  |  |
Accumulated Depreciation |  | $ 132,865,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
510 Madison Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 103,000,000 |  |  |  |
Original Building |  | 253,665,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 50,416,000 |  |  |  |
Land and Improvements |  | 103,000,000 |  |  |  |
Building and Improvements |  | 304,081,000 |  |  |  |
Total |  | 407,081,000 |  |  |  |
Accumulated Depreciation |  | $ 113,410,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
325 Main Street | Office Building [Member] |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances | [7] | $ 0 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 21,596,000 |  |  |  |
Original Building |  | 312,492,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 55,404,000 |  |  |  |
Land and Improvements |  | 21,596,000 |  |  |  |
Building and Improvements |  | 367,896,000 |  |  |  |
Total |  | 389,492,000 |  |  |  |
Accumulated Depreciation |  | $ 35,634,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
680 Folsom Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 72,545,000 |  |  |  |
Original Building |  | 219,766,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 18,167,000 |  |  |  |
Land and Improvements |  | 72,545,000 |  |  |  |
Building and Improvements |  | 237,933,000 |  |  |  |
Total |  | 310,478,000 |  |  |  |
Accumulated Depreciation |  | $ 92,143,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
2200 Pennsylvania Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 183,541,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 125,161,000 |  |  |  |
Land and Improvements |  | 100,592,000 |  |  |  |
Building and Improvements |  | 208,110,000 |  |  |  |
Total |  | 308,702,000 |  |  |  |
Accumulated Depreciation |  | $ 83,117,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
145 Broadway | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 121,000 |  |  |  |
Original Building |  | 273,013,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 26,980,000 |  |  |  |
Land and Improvements |  | 23,367,000 |  |  |  |
Building and Improvements |  | 276,747,000 |  |  |  |
Total |  | 300,114,000 |  |  |  |
Accumulated Depreciation |  | $ 52,401,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
South of Market and Democracy Tower | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 13,603,000 |  |  |  |
Original Building |  | 237,479,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 36,878,000 |  |  |  |
Land and Improvements |  | 13,687,000 |  |  |  |
Building and Improvements |  | 274,273,000 |  |  |  |
Total |  | 287,960,000 |  |  |  |
Accumulated Depreciation |  | $ 128,007,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Bay Colony Corporate Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 18,789,000 |  |  |  |
Original Building |  | 148,451,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 95,783,000 |  |  |  |
Land and Improvements |  | 18,789,000 |  |  |  |
Building and Improvements |  | 241,400,000 |  |  |  |
Land held for development |  | 2,834,000 |  |  |  |
Total |  | 263,023,000 |  |  |  |
Accumulated Depreciation |  | $ 122,700,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
535 Mission Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 40,933,000 |  |  |  |
Original Building |  | 148,378,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 14,409,000 |  |  |  |
Land and Improvements |  | 40,934,000 |  |  |  |
Building and Improvements |  | 162,786,000 |  |  |  |
Total |  | 203,720,000 |  |  |  |
Accumulated Depreciation |  | $ 53,063,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Reservoir Place | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 18,605,000 |  |  |  |
Original Building |  | 104,124,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 65,883,000 |  |  |  |
Land and Improvements |  | 20,108,000 |  |  |  |
Building and Improvements |  | 168,504,000 |  |  |  |
Total |  | 188,612,000 |  |  |  |
Accumulated Depreciation |  | $ 97,426,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
901 New York Avenue | Office Building [Member] |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances |  | $ 197,682,000 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 65,808,000 |  |  |  |
Original Building |  | 72,970,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 45,671,000 |  |  |  |
Land and Improvements |  | 65,808,000 |  |  |  |
Building and Improvements |  | 118,641,000 |  |  |  |
Total |  | 184,449,000 |  |  |  |
Accumulated Depreciation |  | $ 8,414,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Mountain View Research Park | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 95,066,000 |  |  |  |
Original Building |  | 68,373,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 20,266,000 |  |  |  |
Land and Improvements |  | 95,066,000 |  |  |  |
Building and Improvements |  | 88,639,000 |  |  |  |
Total |  | 183,705,000 |  |  |  |
Accumulated Depreciation |  | $ 41,187,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
One Freedom Square | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 9,929,000 |  |  |  |
Original Building |  | 84,504,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 49,956,000 |  |  |  |
Land and Improvements |  | 11,293,000 |  |  |  |
Building and Improvements |  | 133,096,000 |  |  |  |
Total |  | 144,389,000 |  |  |  |
Accumulated Depreciation |  | $ 78,607,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Two Freedom Square | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 13,930,000 |  |  |  |
Original Building |  | 77,739,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 47,125,000 |  |  |  |
Land and Improvements |  | 15,420,000 |  |  |  |
Building and Improvements |  | 123,374,000 |  |  |  |
Total |  | 138,794,000 |  |  |  |
Accumulated Depreciation |  | $ 56,636,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Kingstowne Towne Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 18,021,000 |  |  |  |
Original Building |  | 109,038,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 5,303,000 |  |  |  |
Land and Improvements |  | 18,062,000 |  |  |  |
Building and Improvements |  | 113,370,000 |  |  |  |
Land held for development |  | 930,000 |  |  |  |
Total |  | 132,362,000 |  |  |  |
Accumulated Depreciation |  | $ 61,105,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
One and Two Reston Overlook | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 16,456,000 |  |  |  |
Original Building |  | 66,192,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 48,958,000 |  |  |  |
Land and Improvements |  | 16,179,000 |  |  |  |
Building and Improvements |  | 115,427,000 |  |  |  |
Total |  | 131,606,000 |  |  |  |
Accumulated Depreciation |  | $ 68,795,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Weston Corporate Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 25,753,000 |  |  |  |
Original Building |  | 92,312,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 10,816,000 |  |  |  |
Land and Improvements |  | 25,854,000 |  |  |  |
Building and Improvements |  | 103,027,000 |  |  |  |
Total |  | 128,881,000 |  |  |  |
Accumulated Depreciation |  | $ 47,039,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
1330 Connecticut Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 25,982,000 |  |  |  |
Original Building |  | 82,311,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 18,088,000 |  |  |  |
Land and Improvements |  | 20,792,000 |  |  |  |
Building and Improvements |  | 105,589,000 |  |  |  |
Total |  | 126,381,000 |  |  |  |
Accumulated Depreciation |  | $ 60,339,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Discovery Square | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 11,198,000 |  |  |  |
Original Building |  | 71,782,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 34,141,000 |  |  |  |
Land and Improvements |  | 12,533,000 |  |  |  |
Building and Improvements |  | 104,588,000 |  |  |  |
Total |  | 117,121,000 |  |  |  |
Accumulated Depreciation |  | $ 66,246,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
17Fifty Presidents Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 113,362,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 162,000 |  |  |  |
Land and Improvements |  | 0 |  |  |  |
Building and Improvements |  | 113,524,000 |  |  |  |
Total |  | 113,524,000 |  |  |  |
Accumulated Depreciation |  | $ 25,408,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
355 Main Street | Office Building [Member] |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances |  | $ 596,213,000 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 18,863,000 |  |  |  |
Original Building |  | 53,346,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 38,834,000 |  |  |  |
Land and Improvements |  | 21,173,000 |  |  |  |
Building and Improvements |  | 89,870,000 |  |  |  |
Total |  | 111,043,000 |  |  |  |
Accumulated Depreciation |  | $ 42,355,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Waltham Weston Corporate Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 10,385,000 |  |  |  |
Original Building |  | 60,694,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 25,992,000 |  |  |  |
Land and Improvements |  | 11,097,000 |  |  |  |
Building and Improvements |  | 85,974,000 |  |  |  |
Total |  | 97,071,000 |  |  |  |
Accumulated Depreciation |  | $ 51,285,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Sumner Square | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 624,000 |  |  |  |
Original Building |  | 28,745,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 66,049,000 |  |  |  |
Land and Improvements |  | 27,014,000 |  |  |  |
Building and Improvements |  | 68,404,000 |  |  |  |
Total |  | 95,418,000 |  |  |  |
Accumulated Depreciation |  | $ 32,631,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
10 CityPoint | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 1,953,000 |  |  |  |
Original Building |  | 85,752,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 7,285,000 |  |  |  |
Land and Improvements |  | 2,288,000 |  |  |  |
Building and Improvements |  | 92,702,000 |  |  |  |
Total |  | 94,990,000 |  |  |  |
Accumulated Depreciation |  | $ 29,905,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
90 Broadway | Office Building [Member] |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances | [7] | $ 0 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 19,104,000 |  |  |  |
Original Building |  | 52,078,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 22,168,000 |  |  |  |
Land and Improvements |  | 20,785,000 |  |  |  |
Building and Improvements |  | 72,565,000 |  |  |  |
Total |  | 93,350,000 |  |  |  |
Accumulated Depreciation |  | $ 35,825,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
230 CityPoint | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 13,189,000 |  |  |  |
Original Building |  | 49,823,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 25,922,000 |  |  |  |
Land and Improvements |  | 13,807,000 |  |  |  |
Building and Improvements |  | 75,127,000 |  |  |  |
Total |  | 88,934,000 |  |  |  |
Accumulated Depreciation |  | $ 45,147,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
77 CityPoint | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 13,847,000 |  |  |  |
Original Building |  | 60,383,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 11,356,000 |  |  |  |
Land and Improvements |  | 14,023,000 |  |  |  |
Building and Improvements |  | 71,563,000 |  |  |  |
Total |  | 85,586,000 |  |  |  |
Accumulated Depreciation |  | $ 33,830,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
20 Citypoint | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 4,887,000 |  |  |  |
Original Building |  | 72,764,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 7,072,000 |  |  |  |
Land and Improvements |  | 4,887,000 |  |  |  |
Building and Improvements |  | 79,836,000 |  |  |  |
Total |  | 84,723,000 |  |  |  |
Accumulated Depreciation |  | $ 19,881,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Wisconsin Place | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 53,349,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 26,485,000 |  |  |  |
Land and Improvements |  | 0 |  |  |  |
Building and Improvements |  | 79,834,000 |  |  |  |
Total |  | 79,834,000 |  |  |  |
Accumulated Depreciation |  | $ 33,776,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Shady Grove Innovation District [Member] | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 52,030,000 |  |  |  |
Original Building |  | 64,212,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | (37,955,000) |  |  |  |
Land and Improvements |  | 18,812,000 |  |  |  |
Building and Improvements |  | 24,468,000 |  |  |  |
Land held for development |  | 35,007,000 |  |  |  |
Total |  | 78,287,000 |  |  |  |
Accumulated Depreciation |  | $ 6,279,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
2440 West El Camino Real | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 16,741,000 |  |  |  |
Original Building |  | 51,285,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 6,629,000 |  |  |  |
Land and Improvements |  | 16,741,000 |  |  |  |
Building and Improvements |  | 57,914,000 |  |  |  |
Total |  | 74,655,000 |  |  |  |
Accumulated Depreciation |  | $ 25,436,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
890 Winter Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 13,913,000 |  |  |  |
Original Building |  | 28,557,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 26,191,000 |  |  |  |
Land and Improvements |  | 13,913,000 |  |  |  |
Building and Improvements |  | 54,748,000 |  |  |  |
Total |  | 68,661,000 |  |  |  |
Accumulated Depreciation |  | $ 12,778,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Reston Corporate Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 9,135,000 |  |  |  |
Original Building |  | 50,857,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 4,489,000 |  |  |  |
Land and Improvements |  | 10,148,000 |  |  |  |
Building and Improvements |  | 54,333,000 |  |  |  |
Total |  | 64,481,000 |  |  |  |
Accumulated Depreciation |  | $ 36,950,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
255 Main Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 134,000 |  |  |  |
Original Building |  | 25,110,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 33,909,000 |  |  |  |
Land and Improvements |  | 548,000 |  |  |  |
Building and Improvements |  | 58,605,000 |  |  |  |
Total |  | 59,153,000 |  |  |  |
Accumulated Depreciation |  | $ 47,704,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
University Place | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 37,091,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 13,714,000 |  |  |  |
Land and Improvements |  | 3,435,000 |  |  |  |
Building and Improvements |  | 47,370,000 |  |  |  |
Total |  | 50,805,000 |  |  |  |
Accumulated Depreciation |  | $ 39,872,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Reston Next Office Phase II | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 1,692,000 |  |  |  |
Original Building |  | 46,124,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 0 |  |  |  |
Land and Improvements |  | 1,692,000 |  |  |  |
Building and Improvements |  | 46,124,000 |  |  |  |
Total |  | 47,816,000 |  |  |  |
Accumulated Depreciation |  | $ 642,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Capital Gallery | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 4,725,000 |  |  |  |
Original Building |  | 29,565,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 11,465,000 |  |  |  |
Land and Improvements |  | 8,662,000 |  |  |  |
Building and Improvements |  | 37,093,000 |  |  |  |
Total |  | 45,755,000 |  |  |  |
Accumulated Depreciation |  | $ 25,455,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
150 Broadway | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 850,000 |  |  |  |
Original Building |  | 25,042,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 15,749,000 |  |  |  |
Land and Improvements |  | 1,323,000 |  |  |  |
Building and Improvements |  | 40,318,000 |  |  |  |
Total |  | 41,641,000 |  |  |  |
Accumulated Depreciation |  | $ 21,863,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
North First Business Park | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 23,398,000 |  |  |  |
Original Building |  | 13,069,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 472,000 |  |  |  |
Land and Improvements |  | 17,839,000 |  |  |  |
Building and Improvements |  | 19,100,000 |  |  |  |
Total |  | 36,939,000 |  |  |  |
Accumulated Depreciation |  | $ 18,340,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
105 Broadway | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 1,299,000 |  |  |  |
Original Building |  | 12,943,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 12,723,000 |  |  |  |
Land and Improvements |  | 2,395,000 |  |  |  |
Building and Improvements |  | 24,570,000 |  |  |  |
Total |  | 26,965,000 |  |  |  |
Accumulated Depreciation |  | $ 19,381,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Lexington Office Park | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 998,000 |  |  |  |
Original Building |  | 1,426,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 19,907,000 |  |  |  |
Land and Improvements |  | 1,263,000 |  |  |  |
Building and Improvements |  | 19,393,000 |  |  |  |
Land held for development |  | 1,675,000 |  |  |  |
Total |  | 22,331,000 |  |  |  |
Accumulated Depreciation |  | $ 17,593,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
The Point | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 6,395,000 |  |  |  |
Original Building |  | 10,040,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 546,000 |  |  |  |
Land and Improvements |  | 6,492,000 |  |  |  |
Building and Improvements |  | 10,489,000 |  |  |  |
Total |  | 16,981,000 |  |  |  |
Accumulated Depreciation |  | $ 3,291,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
690 Folsom Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 3,219,000 |  |  |  |
Original Building |  | 11,038,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 1,877,000 |  |  |  |
Land and Improvements |  | 3,219,000 |  |  |  |
Building and Improvements |  | 12,915,000 |  |  |  |
Total |  | 16,134,000 |  |  |  |
Accumulated Depreciation |  | $ 5,165,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
The Avant Retail | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 1,499,000 |  |  |  |
Original Building |  | 6,647,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 2,577,000 |  |  |  |
Land and Improvements |  | 1,499,000 |  |  |  |
Building and Improvements |  | 9,224,000 |  |  |  |
Total |  | 10,723,000 |  |  |  |
Accumulated Depreciation |  | $ 4,104,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
32 Hartwell Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 168,000 |  |  |  |
Original Building |  | 1,943,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 6,394,000 |  |  |  |
Land and Improvements |  | 314,000 |  |  |  |
Building and Improvements |  | 8,191,000 |  |  |  |
Total |  | 8,505,000 |  |  |  |
Accumulated Depreciation |  | $ 3,659,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
453 Ravendale Drive | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 5,477,000 |  |  |  |
Original Building |  | 1,090,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 1,308,000 |  |  |  |
Land and Improvements |  | 5,477,000 |  |  |  |
Building and Improvements |  | 2,398,000 |  |  |  |
Total |  | 7,875,000 |  |  |  |
Accumulated Depreciation |  | $ 1,483,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
125 Broadway | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 126,364,000 |  |  |  |
Original Building |  | 433,662,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 6,496,000 |  |  |  |
Land and Improvements |  | 126,364,000 |  |  |  |
Building and Improvements |  | 440,158,000 |  |  |  |
Total |  | 566,522,000 |  |  |  |
Accumulated Depreciation |  | $ 54,903,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
180 CityPoint [Member] | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 10,908,000 |  |  |  |
Original Building |  | 211,883,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 12,078,000 |  |  |  |
Land and Improvements |  | 10,908,000 |  |  |  |
Building and Improvements |  | 223,961,000 |  |  |  |
Total |  | 234,869,000 |  |  |  |
Accumulated Depreciation |  | $ 14,537,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
300 Binney Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 18,080,000 |  |  |  |
Original Building |  | 51,262,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 157,956,000 |  |  |  |
Land and Improvements |  | 18,080,000 |  |  |  |
Building and Improvements |  | 209,218,000 |  |  |  |
Total |  | 227,298,000 |  |  |  |
Accumulated Depreciation |  | $ 15,427,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
880 Winter Street [Member] | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 15,597,000 |  |  |  |
Original Building |  | 37,255,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 95,618,000 |  |  |  |
Land and Improvements |  | 15,597,000 |  |  |  |
Building and Improvements |  | 132,873,000 |  |  |  |
Total |  | 148,470,000 |  |  |  |
Accumulated Depreciation |  | $ 26,135,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
200 West Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 16,148,000 |  |  |  |
Original Building |  | 24,983,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 79,619,000 |  |  |  |
Land and Improvements |  | 16,813,000 |  |  |  |
Building and Improvements |  | 103,580,000 |  |  |  |
Land held for development |  | 357,000 |  |  |  |
Total |  | 120,750,000 |  |  |  |
Accumulated Depreciation |  | $ 39,547,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
153 & 211 Second Avenue [Member] | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 33,233,000 |  |  |  |
Original Building |  | 55,940,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 3,710,000 |  |  |  |
Land and Improvements |  | 33,233,000 |  |  |  |
Building and Improvements |  | 59,650,000 |  |  |  |
Total |  | 92,883,000 |  |  |  |
Accumulated Depreciation |  | $ 9,161,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
103 CityPoint | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 4,672,000 |  |  |  |
Original Building |  | 77,515,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 93,000 |  |  |  |
Land and Improvements |  | 4,672,000 |  |  |  |
Building and Improvements |  | 77,608,000 |  |  |  |
Total |  | 82,280,000 |  |  |  |
Accumulated Depreciation |  | $ 2,556,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
33 Hayden Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 266,000 |  |  |  |
Original Building |  | 3,234,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 11,506,000 |  |  |  |
Land and Improvements |  | 425,000 |  |  |  |
Building and Improvements |  | 14,576,000 |  |  |  |
Land held for development |  | 5,000 |  |  |  |
Total |  | 15,006,000 |  |  |  |
Accumulated Depreciation |  | $ 11,411,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
92-100 Hayden Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 594,000 |  |  |  |
Original Building |  | 6,748,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 1,909,000 |  |  |  |
Land and Improvements |  | 778,000 |  |  |  |
Building and Improvements |  | 8,473,000 |  |  |  |
Total |  | 9,251,000 |  |  |  |
Accumulated Depreciation |  | $ 7,551,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
250 Binney Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 110,000 |  |  |  |
Original Building |  | 4,483,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 3,593,000 |  |  |  |
Land and Improvements |  | 273,000 |  |  |  |
Building and Improvements |  | 7,913,000 |  |  |  |
Total |  | 8,186,000 |  |  |  |
Accumulated Depreciation |  | $ 7,501,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
The Skylyne | Residential Building |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 239,077,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 1,792,000 |  |  |  |
Land and Improvements |  | 0 |  |  |  |
Building and Improvements |  | 240,869,000 |  |  |  |
Total |  | 240,869,000 |  |  |  |
Accumulated Depreciation |  | $ 32,233,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
The Lofts at Atlantic Wharf | Residential Building |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 3,529,000 |  |  |  |
Original Building |  | 54,891,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 2,598,000 |  |  |  |
Land and Improvements |  | 3,529,000 |  |  |  |
Building and Improvements |  | 57,489,000 |  |  |  |
Total |  | 61,018,000 |  |  |  |
Accumulated Depreciation |  | $ 21,589,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Boston Cambridge Marriott | Hotel [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 478,000 |  |  |  |
Original Building |  | 37,918,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 33,074,000 |  |  |  |
Land and Improvements |  | 1,201,000 |  |  |  |
Building and Improvements |  | 69,640,000 |  |  |  |
Land held for development |  | 629,000 |  |  |  |
Total |  | 71,470,000 |  |  |  |
Accumulated Depreciation |  | $ 55,962,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Kendall Center Green Garage | Garage |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances | [7] | $ 0 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 0 |  |  |  |
Original Building |  | 35,035,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 7,335,000 |  |  |  |
Land and Improvements |  | 103,000 |  |  |  |
Building and Improvements |  | 42,267,000 |  |  |  |
Total |  | 42,370,000 |  |  |  |
Accumulated Depreciation |  | $ 21,209,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
Kendall Center Yellow Garage | Garage |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 1,256,000 |  |  |  |
Original Building |  | 15,697,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 1,674,000 |  |  |  |
Land and Improvements |  | 1,434,000 |  |  |  |
Building and Improvements |  | 17,193,000 |  |  |  |
Total |  | 18,627,000 |  |  |  |
Accumulated Depreciation |  | $ 8,704,000 |  |  |  |
Depreciable Lives (Years) | [6] | (1) |  |  |  |
290 Binney Street | Development |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 888,992,000 |  |  |  |
Land and Improvements |  | 1,054,000 |  |  |  |
Development and Construction in Progress |  | 887,938,000 |  |  |  |
Total |  | $ 888,992,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
343 Madison Avenue | Development |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 377,992,000 |  |  |  |
Land and Improvements |  | 131,898,000 |  |  |  |
Development and Construction in Progress |  | 246,094,000 |  |  |  |
Total |  | $ 377,992,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
121 Broadway | Development |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 273,697,000 |  |  |  |
Development and Construction in Progress |  | 273,697,000 |  |  |  |
Total |  | $ 273,697,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
725 12th Street | Development |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 26,997,000 |  |  |  |
Original Building |  | 8,369,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 19,403,000 |  |  |  |
Development and Construction in Progress |  | 54,769,000 |  |  |  |
Total |  | $ 54,769,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Reston Next Retail | Development |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 15,945,000 |  |  |  |
Land and Improvements |  | 417,000 |  |  |  |
Building and Improvements |  | 2,769,000 |  |  |  |
Development and Construction in Progress |  | 12,759,000 |  |  |  |
Total |  | 15,945,000 |  |  |  |
Accumulated Depreciation |  | $ 66,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
777 Harrison Street | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 144,647,000 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 28,328,000 |  |  |  |
Land held for development |  | 172,975,000 |  |  |  |
Total |  | $ 172,975,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Back Bay Station Master Plan | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 104,811,000 |  |  |  |
Land and Improvements |  | 26,022,000 |  |  |  |
Land held for development |  | 78,789,000 |  |  |  |
Total |  | $ 104,811,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
2100 M Street | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 55,914,000 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 261,000 |  |  |  |
Land held for development |  | 56,175,000 |  |  |  |
Total |  | $ 56,175,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
CityPoint South Master Plan | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 37,749,000 |  |  |  |
Land held for development |  | 37,749,000 |  |  |  |
Total |  | $ 37,749,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
North First Master Plan | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 35,004,000 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | (4,351,000) |  |  |  |
Land held for development |  | 30,653,000 |  |  |  |
Total |  | $ 30,653,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Kendall Center Master Plan | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 17,044,000 |  |  |  |
Land held for development |  | 17,044,000 |  |  |  |
Total |  | $ 17,044,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Reston Gateway Master Plan | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 12,443,000 |  |  |  |
Land held for development |  | 12,443,000 |  |  |  |
Total |  | $ 12,443,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Springfield Metro Center | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 8,868,000 |  |  |  |
Land held for development |  | 8,868,000 |  |  |  |
Total |  | $ 8,868,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Weston Quarry | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 1,516,000 |  |  |  |
Land held for development |  | 1,516,000 |  |  |  |
Total |  | $ 1,516,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Reston Overlook Master Plan | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 82,000 |  |  |  |
Land held for development |  | 82,000 |  |  |  |
Total |  | $ 82,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Boston Properties Limited Partnership |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances | [8] | $ 4,280,067,000 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 5,656,418,000 |  |  |  |
Original Building |  | 15,510,064,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 7,362,066,000 |  |  |  |
Land and Improvements | [9] | 5,826,401,000 |  |  |  |
Building and Improvements | [10] | 20,708,398,000 |  |  |  |
Land held for development | [5] | 518,492,000 | [11] | 714,050,000 |  |
Development and Construction in Progress |  | 1,475,257,000 |  | 764,640,000 |  |
Total |  | 28,528,548,000 |  | 28,154,911,000 | 27,055,206,000 | 25,376,700,000
Accumulated Depreciation |  | 7,869,732,000 |  | 7,355,327,000 | $ 6,718,037,000 | $ 6,143,384,000
Furniture, Fixtures and Equipment |  | 54,160,000 |  | 57,136,000 |  |
Aggregate cost for tax purpose |  | 29,900,000,000 |  |  |  |
Real Estate Aggregate Accumulated Depreciation For Tax Purposes |  | 7,600,000,000 |  |  |  |
Debt Issuance Costs, Net |  | (18,000,000.0) |  |  |  |
Right-of-use assets - finance leases |  | 372,470,000 |  | 372,922,000 |  |
Right of use assets - operating leases |  | $ 325,841,000 |  | $ 334,767,000 |  |
Boston Properties Limited Partnership | Maximum [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Real Estate and Accumulated Depreciation, Life Used for Depreciation |  | 40 years |  |  |  |
Boston Properties Limited Partnership | Furniture, fixtures, and equipment |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Accumulated Depreciation Related to Furniture, Fixtures and Equipment |  | $ 36,897,000 |  |  |  |
Boston Properties Limited Partnership | Land and Land Improvements [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Right-of-use assets - finance leases |  | 349,314,000 |  |  |  |
Right of use assets - operating leases |  | 325,841,000 |  |  |  |
Boston Properties Limited Partnership | Buildings and improvements |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Right-of-use assets - finance leases |  | 23,156,000 |  |  |  |
Boston Properties Limited Partnership | 767Fifth Avenue (the General Motors Building) | Office Building [Member] |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances |  | 2,294,992,000 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 1,796,252,000 |  |  |  |
Original Building |  | 1,532,654,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 423,940,000 |  |  |  |
Land and Improvements |  | 1,796,246,000 |  |  |  |
Building and Improvements |  | 1,956,600,000 |  |  |  |
Total |  | 3,752,846,000 |  |  |  |
Accumulated Depreciation |  | $ 614,923,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Prudential Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 92,077,000 |  |  |  |
Original Building |  | 948,357,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 802,972,000 |  |  |  |
Land and Improvements |  | 100,541,000 |  |  |  |
Building and Improvements |  | 1,742,865,000 |  |  |  |
Total |  | 1,843,406,000 |  |  |  |
Accumulated Depreciation |  | $ 848,999,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Embarcadero Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 179,697,000 |  |  |  |
Original Building |  | 847,410,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 534,868,000 |  |  |  |
Land and Improvements |  | 180,419,000 |  |  |  |
Building and Improvements |  | 1,381,556,000 |  |  |  |
Total |  | 1,561,975,000 |  |  |  |
Accumulated Depreciation |  | $ 850,057,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 399 Park Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 339,200,000 |  |  |  |
Original Building |  | 700,358,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 372,004,000 |  |  |  |
Land and Improvements |  | 339,200,000 |  |  |  |
Building and Improvements |  | 1,072,362,000 |  |  |  |
Total |  | 1,411,562,000 |  |  |  |
Accumulated Depreciation |  | $ 541,561,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 601 Lexington Avenue | Office Building [Member] |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances |  | $ 991,878,000 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 241,600,000 |  |  |  |
Original Building |  | 494,782,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 532,134,000 |  |  |  |
Land and Improvements |  | 279,281,000 |  |  |  |
Building and Improvements |  | 989,235,000 |  |  |  |
Total |  | 1,268,516,000 |  |  |  |
Accumulated Depreciation |  | $ 415,610,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 200 Clarendon Street and Garage | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 219,543,000 |  |  |  |
Original Building |  | 667,884,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 311,929,000 |  |  |  |
Land and Improvements |  | 258,001,000 |  |  |  |
Building and Improvements |  | 941,355,000 |  |  |  |
Total |  | 1,199,356,000 |  |  |  |
Accumulated Depreciation |  | $ 392,736,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Salesforce Tower | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 200,349,000 |  |  |  |
Original Building |  | 946,205,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 4,149,000 |  |  |  |
Land and Improvements |  | 200,349,000 |  |  |  |
Building and Improvements |  | 950,354,000 |  |  |  |
Total |  | 1,150,703,000 |  |  |  |
Accumulated Depreciation |  | $ 214,753,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 250 West 55th Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 285,263,000 |  |  |  |
Original Building |  | 603,167,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 49,995,000 |  |  |  |
Land and Improvements |  | 285,263,000 |  |  |  |
Building and Improvements |  | 653,162,000 |  |  |  |
Total |  | 938,425,000 |  |  |  |
Accumulated Depreciation |  | $ 232,085,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 100 Federal Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 131,067,000 |  |  |  |
Original Building |  | 435,954,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 154,169,000 |  |  |  |
Land and Improvements |  | 131,067,000 |  |  |  |
Building and Improvements |  | 590,123,000 |  |  |  |
Total |  | 721,190,000 |  |  |  |
Accumulated Depreciation |  | $ 209,057,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 7 Times Square | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 165,413,000 |  |  |  |
Original Building |  | 380,438,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 121,935,000 |  |  |  |
Land and Improvements |  | 159,694,000 |  |  |  |
Building and Improvements |  | 508,092,000 |  |  |  |
Total |  | 667,786,000 |  |  |  |
Accumulated Depreciation |  | $ 265,394,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Madison Centre | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 104,641,000 |  |  |  |
Original Building |  | 564,336,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 5,672,000 |  |  |  |
Land and Improvements |  | 104,641,000 |  |  |  |
Building and Improvements |  | 570,008,000 |  |  |  |
Total |  | 674,649,000 |  |  |  |
Accumulated Depreciation |  | $ 76,377,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Santa Monica Business Park [Member] | Office Building [Member] |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances |  | $ 199,302,000 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 46,360,000 |  |  |  |
Original Building |  | 410,421,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 217,684,000 |  |  |  |
Land and Improvements |  | 210,471,000 |  |  |  |
Building and Improvements |  | 462,459,000 |  |  |  |
Land held for development |  | 1,535,000 |  |  |  |
Total |  | 674,465,000 |  |  |  |
Accumulated Depreciation |  | $ 36,680,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Carnegie Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 142,666,000 |  |  |  |
Original Building |  | 316,856,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 180,005,000 |  |  |  |
Land and Improvements |  | 90,501,000 |  |  |  |
Building and Improvements |  | 489,800,000 |  |  |  |
Land held for development |  | 59,226,000 |  |  |  |
Total |  | 639,527,000 |  |  |  |
Accumulated Depreciation |  | $ 288,719,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Reston Next | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 35,549,000 |  |  |  |
Original Building |  | 525,277,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 17,150,000 |  |  |  |
Land and Improvements |  | 2,901,000 |  |  |  |
Building and Improvements |  | 575,075,000 |  |  |  |
Total |  | 577,976,000 |  |  |  |
Accumulated Depreciation |  | $ 69,776,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Atlantic Wharf | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 63,988,000 |  |  |  |
Original Building |  | 454,537,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 45,916,000 |  |  |  |
Land and Improvements |  | 63,988,000 |  |  |  |
Building and Improvements |  | 500,453,000 |  |  |  |
Total |  | 564,441,000 |  |  |  |
Accumulated Depreciation |  | $ 210,601,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 2100 Pennsylvania Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 185,203,000 |  |  |  |
Original Building |  | 324,206,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 5,228,000 |  |  |  |
Land and Improvements |  | 185,203,000 |  |  |  |
Building and Improvements |  | 329,434,000 |  |  |  |
Total |  | 514,637,000 |  |  |  |
Accumulated Depreciation |  | $ 48,475,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 599 Lexington Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 81,040,000 |  |  |  |
Original Building |  | 100,507,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 258,661,000 |  |  |  |
Land and Improvements |  | 81,040,000 |  |  |  |
Building and Improvements |  | 359,168,000 |  |  |  |
Total |  | 440,208,000 |  |  |  |
Accumulated Depreciation |  | $ 208,102,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Fountain Square | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 56,853,000 |  |  |  |
Original Building |  | 306,298,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 60,266,000 |  |  |  |
Land and Improvements |  | 56,853,000 |  |  |  |
Building and Improvements |  | 366,564,000 |  |  |  |
Total |  | 423,417,000 |  |  |  |
Accumulated Depreciation |  | $ 132,865,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 510 Madison Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 103,000,000 |  |  |  |
Original Building |  | 253,665,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 50,416,000 |  |  |  |
Land and Improvements |  | 103,000,000 |  |  |  |
Building and Improvements |  | 304,081,000 |  |  |  |
Total |  | 407,081,000 |  |  |  |
Accumulated Depreciation |  | $ 113,410,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 325 Main Street | Office Building [Member] |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances | [13] | $ 0 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 21,596,000 |  |  |  |
Original Building |  | 312,492,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 55,211,000 |  |  |  |
Land and Improvements |  | 21,403,000 |  |  |  |
Building and Improvements |  | 367,896,000 |  |  |  |
Total |  | 389,299,000 |  |  |  |
Accumulated Depreciation |  | $ 35,634,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 680 Folsom Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 72,545,000 |  |  |  |
Original Building |  | 219,766,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 18,167,000 |  |  |  |
Land and Improvements |  | 72,545,000 |  |  |  |
Building and Improvements |  | 237,933,000 |  |  |  |
Total |  | 310,478,000 |  |  |  |
Accumulated Depreciation |  | $ 92,143,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 2200 Pennsylvania Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 183,541,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 125,161,000 |  |  |  |
Land and Improvements |  | 100,592,000 |  |  |  |
Building and Improvements |  | 208,110,000 |  |  |  |
Total |  | 308,702,000 |  |  |  |
Accumulated Depreciation |  | $ 83,114,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 145 Broadway | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 121,000 |  |  |  |
Original Building |  | 273,013,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 26,777,000 |  |  |  |
Land and Improvements |  | 23,164,000 |  |  |  |
Building and Improvements |  | 276,747,000 |  |  |  |
Total |  | 299,911,000 |  |  |  |
Accumulated Depreciation |  | $ 52,401,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | South of Market and Democracy Tower | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 13,603,000 |  |  |  |
Original Building |  | 237,479,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 36,542,000 |  |  |  |
Land and Improvements |  | 13,603,000 |  |  |  |
Building and Improvements |  | 274,021,000 |  |  |  |
Total |  | 287,624,000 |  |  |  |
Accumulated Depreciation |  | $ 127,897,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Bay Colony Corporate Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 18,789,000 |  |  |  |
Original Building |  | 148,451,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 95,783,000 |  |  |  |
Land and Improvements |  | 18,789,000 |  |  |  |
Building and Improvements |  | 241,400,000 |  |  |  |
Land held for development |  | 2,834,000 |  |  |  |
Total |  | 263,023,000 |  |  |  |
Accumulated Depreciation |  | $ 122,700,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 535 Mission Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 40,933,000 |  |  |  |
Original Building |  | 148,378,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 14,409,000 |  |  |  |
Land and Improvements |  | 40,934,000 |  |  |  |
Building and Improvements |  | 162,786,000 |  |  |  |
Total |  | 203,720,000 |  |  |  |
Accumulated Depreciation |  | $ 53,063,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Reservoir Place | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 18,605,000 |  |  |  |
Original Building |  | 104,124,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 61,808,000 |  |  |  |
Land and Improvements |  | 19,089,000 |  |  |  |
Building and Improvements |  | 165,448,000 |  |  |  |
Total |  | 184,537,000 |  |  |  |
Accumulated Depreciation |  | $ 95,892,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 901 New York Avenue | Office Building [Member] |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances |  | $ 197,682,000 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 65,808,000 |  |  |  |
Original Building |  | 72,970,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 45,671,000 |  |  |  |
Land and Improvements |  | 65,808,000 |  |  |  |
Building and Improvements |  | 118,641,000 |  |  |  |
Total |  | 184,449,000 |  |  |  |
Accumulated Depreciation |  | $ 8,414,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Mountain View Research Park | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 95,066,000 |  |  |  |
Original Building |  | 68,373,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 20,266,000 |  |  |  |
Land and Improvements |  | 95,066,000 |  |  |  |
Building and Improvements |  | 88,639,000 |  |  |  |
Total |  | 183,705,000 |  |  |  |
Accumulated Depreciation |  | $ 41,187,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | One Freedom Square | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 9,929,000 |  |  |  |
Original Building |  | 84,504,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 44,319,000 |  |  |  |
Land and Improvements |  | 9,883,000 |  |  |  |
Building and Improvements |  | 128,869,000 |  |  |  |
Total |  | 138,752,000 |  |  |  |
Accumulated Depreciation |  | $ 76,485,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Two Freedom Square | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 13,930,000 |  |  |  |
Original Building |  | 77,739,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 40,913,000 |  |  |  |
Land and Improvements |  | 13,866,000 |  |  |  |
Building and Improvements |  | 118,716,000 |  |  |  |
Total |  | 132,582,000 |  |  |  |
Accumulated Depreciation |  | $ 54,297,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Kingstowne Towne Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 18,021,000 |  |  |  |
Original Building |  | 109,038,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 5,139,000 |  |  |  |
Land and Improvements |  | 18,021,000 |  |  |  |
Building and Improvements |  | 113,247,000 |  |  |  |
Land held for development |  | 930,000 |  |  |  |
Total |  | 132,198,000 |  |  |  |
Accumulated Depreciation |  | $ 61,050,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | One and Two Reston Overlook | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 16,456,000 |  |  |  |
Original Building |  | 66,192,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 44,540,000 |  |  |  |
Land and Improvements |  | 15,074,000 |  |  |  |
Building and Improvements |  | 112,114,000 |  |  |  |
Total |  | 127,188,000 |  |  |  |
Accumulated Depreciation |  | $ 67,131,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Weston Corporate Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 25,753,000 |  |  |  |
Original Building |  | 92,312,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 10,816,000 |  |  |  |
Land and Improvements |  | 25,854,000 |  |  |  |
Building and Improvements |  | 103,027,000 |  |  |  |
Total |  | 128,881,000 |  |  |  |
Accumulated Depreciation |  | $ 47,039,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 1330 Connecticut Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 25,982,000 |  |  |  |
Original Building |  | 82,311,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 18,088,000 |  |  |  |
Land and Improvements |  | 20,792,000 |  |  |  |
Building and Improvements |  | 105,589,000 |  |  |  |
Total |  | 126,381,000 |  |  |  |
Accumulated Depreciation |  | $ 60,339,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Discovery Square | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 11,198,000 |  |  |  |
Original Building |  | 71,782,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 28,596,000 |  |  |  |
Land and Improvements |  | 11,146,000 |  |  |  |
Building and Improvements |  | 100,430,000 |  |  |  |
Total |  | 111,576,000 |  |  |  |
Accumulated Depreciation |  | $ 64,158,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 17Fifty Presidents Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 113,362,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 162,000 |  |  |  |
Land and Improvements |  | 0 |  |  |  |
Building and Improvements |  | 113,524,000 |  |  |  |
Total |  | 113,524,000 |  |  |  |
Accumulated Depreciation |  | $ 25,408,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 355 Main Street | Office Building [Member] |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances |  | $ 596,213,000 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 18,863,000 |  |  |  |
Original Building |  | 53,346,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 38,536,000 |  |  |  |
Land and Improvements |  | 21,098,000 |  |  |  |
Building and Improvements |  | 89,647,000 |  |  |  |
Total |  | 110,745,000 |  |  |  |
Accumulated Depreciation |  | $ 42,245,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Waltham Weston Corporate Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 10,385,000 |  |  |  |
Original Building |  | 60,694,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 23,005,000 |  |  |  |
Land and Improvements |  | 10,350,000 |  |  |  |
Building and Improvements |  | 83,734,000 |  |  |  |
Total |  | 94,084,000 |  |  |  |
Accumulated Depreciation |  | $ 50,160,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Sumner Square | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 624,000 |  |  |  |
Original Building |  | 28,745,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 63,969,000 |  |  |  |
Land and Improvements |  | 26,494,000 |  |  |  |
Building and Improvements |  | 66,844,000 |  |  |  |
Total |  | 93,338,000 |  |  |  |
Accumulated Depreciation |  | $ 31,851,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 10 CityPoint | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 1,953,000 |  |  |  |
Original Building |  | 85,752,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 7,124,000 |  |  |  |
Land and Improvements |  | 2,127,000 |  |  |  |
Building and Improvements |  | 92,702,000 |  |  |  |
Total |  | 94,829,000 |  |  |  |
Accumulated Depreciation |  | $ 29,905,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 90 Broadway | Office Building [Member] |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances | [13] | $ 0 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 19,104,000 |  |  |  |
Original Building |  | 52,078,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 21,989,000 |  |  |  |
Land and Improvements |  | 20,741,000 |  |  |  |
Building and Improvements |  | 72,430,000 |  |  |  |
Total |  | 93,171,000 |  |  |  |
Accumulated Depreciation |  | $ 35,765,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 230 CityPoint | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 13,189,000 |  |  |  |
Original Building |  | 49,823,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 24,305,000 |  |  |  |
Land and Improvements |  | 13,403,000 |  |  |  |
Building and Improvements |  | 73,914,000 |  |  |  |
Total |  | 87,317,000 |  |  |  |
Accumulated Depreciation |  | $ 44,541,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 77 CityPoint | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 13,847,000 |  |  |  |
Original Building |  | 60,383,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 11,251,000 |  |  |  |
Land and Improvements |  | 13,997,000 |  |  |  |
Building and Improvements |  | 71,484,000 |  |  |  |
Total |  | 85,481,000 |  |  |  |
Accumulated Depreciation |  | $ 33,795,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 20 Citypoint | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 4,887,000 |  |  |  |
Original Building |  | 72,764,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 7,072,000 |  |  |  |
Land and Improvements |  | 4,887,000 |  |  |  |
Building and Improvements |  | 79,836,000 |  |  |  |
Total |  | 84,723,000 |  |  |  |
Accumulated Depreciation |  | $ 19,881,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Wisconsin Place | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 53,349,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 26,485,000 |  |  |  |
Land and Improvements |  | 0 |  |  |  |
Building and Improvements |  | 79,834,000 |  |  |  |
Total |  | 79,834,000 |  |  |  |
Accumulated Depreciation |  | $ 33,776,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Shady Grove Innovation District [Member] | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 52,030,000 |  |  |  |
Original Building |  | 64,212,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | (37,955,000) |  |  |  |
Land and Improvements |  | 18,812,000 |  |  |  |
Building and Improvements |  | 24,468,000 |  |  |  |
Land held for development |  | 35,007,000 |  |  |  |
Total |  | 78,287,000 |  |  |  |
Accumulated Depreciation |  | $ 6,279,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 2440 West El Camino Real | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 16,741,000 |  |  |  |
Original Building |  | 51,285,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 6,629,000 |  |  |  |
Land and Improvements |  | 16,741,000 |  |  |  |
Building and Improvements |  | 57,914,000 |  |  |  |
Total |  | 74,655,000 |  |  |  |
Accumulated Depreciation |  | $ 25,436,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 890 Winter Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 13,913,000 |  |  |  |
Original Building |  | 28,557,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 26,191,000 |  |  |  |
Land and Improvements |  | 13,913,000 |  |  |  |
Building and Improvements |  | 54,748,000 |  |  |  |
Total |  | 68,661,000 |  |  |  |
Accumulated Depreciation |  | $ 12,778,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Reston Corporate Center | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 9,135,000 |  |  |  |
Original Building |  | 50,857,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 1,878,000 |  |  |  |
Land and Improvements |  | 9,496,000 |  |  |  |
Building and Improvements |  | 52,374,000 |  |  |  |
Total |  | 61,870,000 |  |  |  |
Accumulated Depreciation |  | $ 35,966,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 255 Main Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 134,000 |  |  |  |
Original Building |  | 25,110,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 32,253,000 |  |  |  |
Land and Improvements |  | 134,000 |  |  |  |
Building and Improvements |  | 57,363,000 |  |  |  |
Total |  | 57,497,000 |  |  |  |
Accumulated Depreciation |  | $ 47,083,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | University Place | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 37,091,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 12,264,000 |  |  |  |
Land and Improvements |  | 3,435,000 |  |  |  |
Building and Improvements |  | 45,920,000 |  |  |  |
Total |  | 49,355,000 |  |  |  |
Accumulated Depreciation |  | $ 38,664,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Reston Next Office Phase II | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 1,692,000 |  |  |  |
Original Building |  | 46,124,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 0 |  |  |  |
Land and Improvements |  | 1,692,000 |  |  |  |
Building and Improvements |  | 46,124,000 |  |  |  |
Total |  | 47,816,000 |  |  |  |
Accumulated Depreciation |  | $ 642,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Capital Gallery | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 4,725,000 |  |  |  |
Original Building |  | 29,565,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 6,802,000 |  |  |  |
Land and Improvements |  | 6,128,000 |  |  |  |
Building and Improvements |  | 34,964,000 |  |  |  |
Total |  | 41,092,000 |  |  |  |
Accumulated Depreciation |  | $ 24,387,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 150 Broadway | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 850,000 |  |  |  |
Original Building |  | 25,042,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 13,744,000 |  |  |  |
Land and Improvements |  | 822,000 |  |  |  |
Building and Improvements |  | 38,814,000 |  |  |  |
Total |  | 39,636,000 |  |  |  |
Accumulated Depreciation |  | $ 21,104,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | North First Business Park | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 23,398,000 |  |  |  |
Original Building |  | 13,069,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 472,000 |  |  |  |
Land and Improvements |  | 17,839,000 |  |  |  |
Building and Improvements |  | 19,100,000 |  |  |  |
Total |  | 36,939,000 |  |  |  |
Accumulated Depreciation |  | $ 18,340,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 105 Broadway | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 1,299,000 |  |  |  |
Original Building |  | 12,943,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 10,617,000 |  |  |  |
Land and Improvements |  | 1,868,000 |  |  |  |
Building and Improvements |  | 22,991,000 |  |  |  |
Total |  | 24,859,000 |  |  |  |
Accumulated Depreciation |  | $ 18,588,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Lexington Office Park | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 998,000 |  |  |  |
Original Building |  | 1,426,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 19,143,000 |  |  |  |
Land and Improvements |  | 1,072,000 |  |  |  |
Building and Improvements |  | 18,820,000 |  |  |  |
Land held for development |  | 1,675,000 |  |  |  |
Total |  | 21,567,000 |  |  |  |
Accumulated Depreciation |  | $ 17,309,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | The Point | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 6,395,000 |  |  |  |
Original Building |  | 10,040,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 546,000 |  |  |  |
Land and Improvements |  | 6,492,000 |  |  |  |
Building and Improvements |  | 10,489,000 |  |  |  |
Total |  | 16,981,000 |  |  |  |
Accumulated Depreciation |  | $ 3,291,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 690 Folsom Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 3,219,000 |  |  |  |
Original Building |  | 11,038,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 1,877,000 |  |  |  |
Land and Improvements |  | 3,219,000 |  |  |  |
Building and Improvements |  | 12,915,000 |  |  |  |
Total |  | 16,134,000 |  |  |  |
Accumulated Depreciation |  | $ 5,165,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | The Avant Retail | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 1,499,000 |  |  |  |
Original Building |  | 6,647,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 2,577,000 |  |  |  |
Land and Improvements |  | 1,499,000 |  |  |  |
Building and Improvements |  | 9,224,000 |  |  |  |
Total |  | 10,723,000 |  |  |  |
Accumulated Depreciation |  | $ 4,104,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 32 Hartwell Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 168,000 |  |  |  |
Original Building |  | 1,943,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 5,808,000 |  |  |  |
Land and Improvements |  | 168,000 |  |  |  |
Building and Improvements |  | 7,751,000 |  |  |  |
Total |  | 7,919,000 |  |  |  |
Accumulated Depreciation |  | $ 3,437,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 453 Ravendale Drive | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 5,477,000 |  |  |  |
Original Building |  | 1,090,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 1,308,000 |  |  |  |
Land and Improvements |  | 5,477,000 |  |  |  |
Building and Improvements |  | 2,398,000 |  |  |  |
Total |  | 7,875,000 |  |  |  |
Accumulated Depreciation |  | $ 1,483,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 125 Broadway | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 126,364,000 |  |  |  |
Original Building |  | 433,662,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 6,496,000 |  |  |  |
Land and Improvements |  | 126,364,000 |  |  |  |
Building and Improvements |  | 440,158,000 |  |  |  |
Total |  | 566,522,000 |  |  |  |
Accumulated Depreciation |  | $ 54,903,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 180 CityPoint [Member] | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 10,908,000 |  |  |  |
Original Building |  | 211,883,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 12,078,000 |  |  |  |
Land and Improvements |  | 10,908,000 |  |  |  |
Building and Improvements |  | 223,961,000 |  |  |  |
Total |  | 234,869,000 |  |  |  |
Accumulated Depreciation |  | $ 14,537,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 300 Binney Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 18,080,000 |  |  |  |
Original Building |  | 51,262,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 157,956,000 |  |  |  |
Land and Improvements |  | 18,080,000 |  |  |  |
Building and Improvements |  | 209,218,000 |  |  |  |
Total |  | 227,298,000 |  |  |  |
Accumulated Depreciation |  | $ 15,427,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 880 Winter Street [Member] | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 15,597,000 |  |  |  |
Original Building |  | 37,255,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 95,618,000 |  |  |  |
Land and Improvements |  | 15,597,000 |  |  |  |
Building and Improvements |  | 132,873,000 |  |  |  |
Total |  | 148,470,000 |  |  |  |
Accumulated Depreciation |  | $ 26,135,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 200 West Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 16,148,000 |  |  |  |
Original Building |  | 24,983,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 76,958,000 |  |  |  |
Land and Improvements |  | 16,148,000 |  |  |  |
Building and Improvements |  | 101,584,000 |  |  |  |
Land held for development |  | 357,000 |  |  |  |
Total |  | 118,089,000 |  |  |  |
Accumulated Depreciation |  | $ 38,545,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 153 & 211 Second Avenue [Member] | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 33,233,000 |  |  |  |
Original Building |  | 55,940,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 3,710,000 |  |  |  |
Land and Improvements |  | 33,233,000 |  |  |  |
Building and Improvements |  | 59,650,000 |  |  |  |
Total |  | 92,883,000 |  |  |  |
Accumulated Depreciation |  | $ 9,161,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 103 CityPoint | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 4,672,000 |  |  |  |
Original Building |  | 77,515,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 91,000 |  |  |  |
Land and Improvements |  | 4,670,000 |  |  |  |
Building and Improvements |  | 77,608,000 |  |  |  |
Total |  | 82,278,000 |  |  |  |
Accumulated Depreciation |  | $ 2,556,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 33 Hayden Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 266,000 |  |  |  |
Original Building |  | 3,234,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 10,869,000 |  |  |  |
Land and Improvements |  | 266,000 |  |  |  |
Building and Improvements |  | 14,098,000 |  |  |  |
Land held for development |  | 5,000 |  |  |  |
Total |  | 14,369,000 |  |  |  |
Accumulated Depreciation |  | $ 11,171,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 92-100 Hayden Avenue | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 594,000 |  |  |  |
Original Building |  | 6,748,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 1,180,000 |  |  |  |
Land and Improvements |  | 595,000 |  |  |  |
Building and Improvements |  | 7,927,000 |  |  |  |
Total |  | 8,522,000 |  |  |  |
Accumulated Depreciation |  | $ 7,275,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 250 Binney Street | Office Building [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 110,000 |  |  |  |
Original Building |  | 4,483,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 2,939,000 |  |  |  |
Land and Improvements |  | 110,000 |  |  |  |
Building and Improvements |  | 7,422,000 |  |  |  |
Total |  | 7,532,000 |  |  |  |
Accumulated Depreciation |  | $ 7,259,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | The Skylyne | Residential Building |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 239,077,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 1,792,000 |  |  |  |
Building and Improvements |  | 240,869,000 |  |  |  |
Total |  | 240,869,000 |  |  |  |
Accumulated Depreciation |  | $ 32,233,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | The Lofts at Atlantic Wharf | Residential Building |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 3,529,000 |  |  |  |
Original Building |  | 54,891,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 2,598,000 |  |  |  |
Land and Improvements |  | 3,529,000 |  |  |  |
Building and Improvements |  | 57,489,000 |  |  |  |
Total |  | 61,018,000 |  |  |  |
Accumulated Depreciation |  | $ 21,589,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Boston Cambridge Marriott | Hotel [Member] |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 478,000 |  |  |  |
Original Building |  | 37,918,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 30,183,000 |  |  |  |
Land and Improvements |  | 478,000 |  |  |  |
Building and Improvements |  | 67,472,000 |  |  |  |
Land held for development |  | 629,000 |  |  |  |
Total |  | 68,579,000 |  |  |  |
Accumulated Depreciation |  | $ 54,874,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Kendall Center Green Garage | Garage |  |  |  |  |  |
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |  |
Encumbrances | [13] | $ 0 |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | 0 |  |  |  |
Original Building |  | 35,035,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 6,921,000 |  |  |  |
Building and Improvements |  | 41,956,000 |  |  |  |
Total |  | 41,956,000 |  |  |  |
Accumulated Depreciation |  | $ 21,055,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | Kendall Center Yellow Garage | Garage |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 1,256,000 |  |  |  |
Original Building |  | 15,697,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 962,000 |  |  |  |
Land and Improvements |  | 1,256,000 |  |  |  |
Building and Improvements |  | 16,659,000 |  |  |  |
Total |  | 17,915,000 |  |  |  |
Accumulated Depreciation |  | $ 8,439,000 |  |  |  |
Depreciable Lives (Years) | [12] | (1) |  |  |  |
Boston Properties Limited Partnership | 290 Binney Street | Development |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 888,576,000 |  |  |  |
Land and Improvements |  | 638,000 |  |  |  |
Development and Construction in Progress |  | 887,938,000 |  |  |  |
Total |  | $ 888,576,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Boston Properties Limited Partnership | 343 Madison Avenue | Development |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 377,992,000 |  |  |  |
Land and Improvements |  | 131,898,000 |  |  |  |
Development and Construction in Progress |  | 246,094,000 |  |  |  |
Total |  | $ 377,992,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Boston Properties Limited Partnership | 121 Broadway | Development |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 273,697,000 |  |  |  |
Development and Construction in Progress |  | 273,697,000 |  |  |  |
Total |  | $ 273,697,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Boston Properties Limited Partnership | 725 12th Street | Development |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 26,997,000 |  |  |  |
Original Building |  | 8,369,000 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 19,403,000 |  |  |  |
Development and Construction in Progress |  | 54,769,000 |  |  |  |
Total |  | $ 54,769,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Boston Properties Limited Partnership | Reston Next Retail | Development |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 15,945,000 |  |  |  |
Land and Improvements |  | 417,000 |  |  |  |
Building and Improvements |  | 2,769,000 |  |  |  |
Development and Construction in Progress |  | 12,759,000 |  |  |  |
Total |  | 15,945,000 |  |  |  |
Accumulated Depreciation |  | $ 66,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Boston Properties Limited Partnership | 777 Harrison Street | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 144,647,000 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 28,328,000 |  |  |  |
Land held for development |  | 172,975,000 |  |  |  |
Total |  | $ 172,975,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Boston Properties Limited Partnership | Back Bay Station Master Plan | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 104,811,000 |  |  |  |
Land and Improvements |  | 26,022,000 |  |  |  |
Land held for development |  | 78,789,000 |  |  |  |
Total |  | $ 104,811,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Boston Properties Limited Partnership | 2100 M Street | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 55,914,000 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 261,000 |  |  |  |
Land held for development |  | 56,175,000 |  |  |  |
Total |  | $ 56,175,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Boston Properties Limited Partnership | CityPoint South Master Plan | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 37,749,000 |  |  |  |
Land held for development |  | 37,749,000 |  |  |  |
Total |  | $ 37,749,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Boston Properties Limited Partnership | North First Master Plan | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 35,004,000 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | (4,351,000) |  |  |  |
Land held for development |  | 30,653,000 |  |  |  |
Total |  | $ 30,653,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Boston Properties Limited Partnership | Kendall Center Master Plan | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 17,044,000 |  |  |  |
Land held for development |  | 17,044,000 |  |  |  |
Total |  | $ 17,044,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Boston Properties Limited Partnership | Reston Gateway Master Plan | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 12,443,000 |  |  |  |
Land held for development |  | 12,443,000 |  |  |  |
Total |  | $ 12,443,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Boston Properties Limited Partnership | Springfield Metro Center | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 8,868,000 |  |  |  |
Land held for development |  | 8,868,000 |  |  |  |
Total |  | $ 8,868,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Boston Properties Limited Partnership | Weston Quarry | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 1,516,000 |  |  |  |
Land held for development |  | 1,516,000 |  |  |  |
Total |  | $ 1,516,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
Boston Properties Limited Partnership | Reston Overlook Master Plan | Land |  |  |  |  |  |
Original Cost |  |  |  |  |  |
Original Land |  | $ 0 |  |  |  |
Original Building |  | 0 |  |  |  |
Costs Capitalized Subsequent to Acquisition |  | 82,000 |  |  |  |
Land held for development |  | 82,000 |  |  |  |
Total |  | $ 82,000 |  |  |  |
Depreciable Lives (Years) |  | N/A |  |  |  |
[1] | Includes unamortized deferred financing costs totaling approximately $(18.0) million.
[2] | Includes Right of Use Assets - Finance Leases and Right of Use Assets - Operating Leases of approximately $349,314 and $325,841, respectively.
[3] | Includes Right of Use Assets - Finance Leases of approximately $23,156.
[4] | Includes pre-development costs.
[5] | Includes pre-development costs.
[6] | Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.
[7] | This property is encumbered with the mortgage note shown at 355 Main Street.
[8] | Includes unamortized deferred financing costs totaling approximately $(18.0) million.
[9] | Includes Right of Use Assets - Finance Leases and Right of Use Assets - Operating Leases of approximately $349,314 and $325,841, respectively.
[10] | Includes Right of Use Assets - Finance Leases of approximately $23,156.
[11] | Includes pre-development costs.
[12] | Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.
[13] | This property is encumbered with the mortgage note shown at 355 Main Street.

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