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Real Estate Dispositions, Held for Sale, and Impairment Charges - Components of Income from Real Estate and Related Assets Held for Sale (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Real Estate Properties [Line Items] |  |  |
Impairment charge | $ 3,621 | $ 1,813 | $ 0
Real Estate Held for Sale |  |  |
Real Estate Properties [Line Items] |  |  |
Operating revenue | 1,861 | 1,769 | 1,288
Operating expense | 2,938 | 985 | 792
Other income, net | (388) | (364) | (394)
Income (expense) from real estate and related assets sold | (1,465) | 420 | $ 102
Impairment charge | $ 1,900 | $ 1,800 |

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- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2420-110228 + Details
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- Definition Amount of operating expense attributable to disposal group, including, but not limited to, discontinued operation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 5B -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721673-107760 + Details
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- Definition Amount of revenue attributable to disposal group, including, but not limited to, discontinued operation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 5B -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721673-107760 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721683-107760 + Details
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