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Schedule III: Real Estate and Accumulated Depreciation (Rollforward of Real Estate and Accumulated Deprecation) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
REAL ESTATE: |  |  |
Balance at beginning of period | $ 1,037,368 | $ 1,033,551 | $ 1,029,472
Subtotal real estate | 1,041,281 | 1,037,368 | 1,035,230
Less: Fully depreciated assets | (13,590) | 0 | (1,679)
Balance at end of the period | 1,027,691 | 1,037,368 | 1,033,551
ACCUMULATED DEPRECIATION: |  |  |
Balance at beginning of period | 283,044 | 252,737 | 225,533
Additions charged to operating expenses | 27,967 | 30,307 | 28,883
Subtotal of accumulated depreciation | 311,011 | 283,044 | 254,416
Less: Fully depreciated assets | (13,590) | 0 | (1,679)
Balance at end of the period | 297,421 | 283,044 | 252,737
Land |  |  |
REAL ESTATE: |  |  |
Changes during the period | 0 | 0 | 0
Buildings and leasehold improvements |  |  |
REAL ESTATE: |  |  |
Changes during the period | 3,218 | 3,046 | 12,464
Development and construction in progress |  |  |
REAL ESTATE: |  |  |
Changes during the period | $ 695 | $ 771 |
Changes during the period |  |  | $ (6,706)

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- Definition The subtotal of accumulated depreciation balance excluding accumulated depreciation on assets sold and write-off of accumulated depreciation on fully depreciated assets. + References No definition available. + Details
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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/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28(Column F)) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
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- Definition Amount of other additions to accumulated depreciation other than depreciation expense for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28(Footnote 4)) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
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- Definition Amount of decrease to accumulated depreciation for real estate investments sold for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28(Footnote 4)) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
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- Definition Amount, before accumulated depreciation, of real estate investment by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate. Excludes real estate not held as investment or interest. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28(Column E)) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
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- Definition Amount of increase in real estate investments related to improvements for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28(Footnote 4)) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
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- Definition Amount of other deductions to real estate investments, excluding sales, for entities with a substantial portion of business acquiring and holding investment real estate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28(Footnote 4)) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
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