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Schedule III: Rollforward of Real Estate Assets and Accumulated Depreciation (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Real Estate and Accumulated Depreciation [Line Items] |  |  |
Balance at beginning of period | $ 993,927 | $ 919,576 | $ 911,792
Subtotal real estate | 1,040,662 | 993,984 | 919,576
Less: Fully depreciated assets | (11,190) | (57) | 0
Balance at end of the period | 1,029,472 | 993,927 | 919,576
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward] |  |  |
Balance at beginning of period | 210,025 | 185,375 | 160,826
Additions charged to operating expenses | 26,698 | 24,707 | 24,549
Subtotal of accumulated depreciation | 236,723 | 210,082 | 185,375
Less: Fully depreciated assets | (11,190) | (57) | 0
Balance at end of the period | 225,533 | 210,025 | 185,375
Land [Member] |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |
Real Estate, Improvements | 0 | 0 | 0
Buildings and leasehold improvements [Member] |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |
Real Estate, Improvements | 112,538 | 4,043 | 5,072
Development and construction in progress [Member] |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |
Real Estate, Improvements | $ (65,803) | $ 70,365 | $ 2,712

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- Definition Amount of accumulated depreciation pertaining to real estate investments for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28.FN4) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule III) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
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