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Investments in Unconsolidated Joint Ventures (Statements of Operations of the Joint Ventures) (Details) - USD ($) $ in Thousands |  | 3 Months Ended | 9 Months Ended
--- | --- | --- | ---
Jun. 27, 2019 | Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2019 | Sep. 30, 2018
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Total revenue |  |  | $ 743,553 |  | $ 686,284 | $ 2,203,061 |  | $ 2,011,919
Expenses |  |  |  |  |  |  |  |
Depreciation and amortization |  |  | 165,862 |  | 157,996 | 507,867 |  | 480,210
Total expenses |  |  | 474,322 |  | 447,920 | 1,432,266 |  | 1,334,779
Other expense |  |  |  |  |  |  |  |
Interest expense |  |  | (106,471) |  | (95,366) | (309,837) |  | (277,790)
Gains (loss) on sales of real estate |  |  | (15) |  | 7,863 | 766 |  | 122,552
Net income |  |  | 141,370 |  | 150,445 | 475,990 |  | 527,322
Income (loss) from unconsolidated joint ventures |  |  | (649) |  | (4,313) | 47,528 |  | (3,083)
Unconsolidated Joint Ventures [Member] |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Total revenue | [1] |  | 75,940 |  | 76,177 | 239,099 |  | 189,759
Expenses |  |  |  |  |  |  |  |
Operating |  |  | 28,839 |  | 29,522 | 89,472 |  | 75,239
Depreciation and amortization |  |  | 23,477 |  | 44,993 | 76,941 |  | 74,245
Total expenses |  |  | 52,316 |  | 74,515 | 166,413 |  | 149,484
Other expense |  |  |  |  |  |  |  |
Interest expense |  |  | (20,483) |  | (19,861) | (62,043) |  | (48,993)
Gains (loss) on sales of real estate |  |  | (812) | [2] | 0 | 33,760 | [2] | 0
Net income |  |  | 2,329 |  | (18,199) | 44,403 |  | (8,718)
Company's share of net income (loss) |  |  | 392 |  | (2,858) | 24,352 |  | 1,073
Basis differential | [2],[3] |  | (1,041) |  | (1,455) | 23,176 |  | (4,156)
Income (loss) from unconsolidated joint ventures |  |  | (649) |  | (4,313) | 47,528 |  | (3,083)
Straight-line rent adjustments |  |  | 5,300 |  | 4,800 | 18,700 |  | 9,800
540 Madison Venture LLC [Member] |  |  |  |  |  |  |  |
Other expense |  |  |  |  |  |  |  |
Equity Method Investment, Realized Gain (Loss) on Disposal |  | $ 47,300 | (500) |  |  |  |  |
Colorado Center [Member] | Unconsolidated Joint Ventures [Member] |  |  |  |  |  |  |  |
Other expense |  |  |  |  |  |  |  |
Straight-line rent adjustments |  |  | 500 |  | 500 | 1,600 |  | 1,900
"Above" and "below" market rent adjustments, net |  |  | $ 400 |  | $ 400 | $ 1,300 |  | $ 1,200
[1] | Includes straight-line rent adjustments of approximately $5.3 million and $4.8 million for the three months ended September 30, 2019 and 2018, respectively, and $18.7 million and $9.8 million for the nine months ended September 30, 2019 and 2018, respectively.
[2] | Represents the total gain on sale of 540 Madison Avenue recognized by the joint venture, as described below. During 2008, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture resulting in a basis differential between the carrying value of the Company’s investment in the joint venture and the joint venture’s basis in the assets and liabilities of the property. As a result of the historical basis difference, the Company recognized a gain on sale of real estate totaling approximately $47.3 million for the nine months ended September 30, 2019, which consists of its share of the gain on sale reported by the joint venture as well as an adjustment for the basis differential. The Company recognized a reduction to the gain on sale of real estate totaling approximately $0.5 million for the three months ended September 30, 2019. The gain on sale is included in Income (Loss) from Unconsolidated Joint Ventures in the Company’s Consolidated Statements of Operations.
[3] | Includes straight-line rent adjustments of approximately $0.5 million and $0.5 million for the three months ended September 30, 2019 and 2018, respectively, and $1.6 million and $1.9 million for the nine months ended September 30, 2019 and 2018, respectively. Also includes net above-/below-market rent adjustments of approximately $0.4 million and $0.4 million for the three months ended September 30, 2019 and 2018, respectively, and $1.3 million and $1.2 million for the nine months ended September 30, 2019 and 2018, respectively

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