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Real Estate Dispositions, Held for Sale, and Impairment Charges - Additional Information (Detail) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2017 USD ($) | Jun. 30, 2017 USD ($) | Mar. 31, 2017 USD ($) | Dec. 31, 2017 USD ($) property | Dec. 31, 2016 USD ($) property | Dec. 31, 2015 USD ($) property
Schedule Of Real Estate Owned Held For Sale [Line Items] |  |  |  |  |  |
Number of impaired assets, held and used |  |  |  | 2 | 1 |
Impairment charge | $ |  |  | $ 3,700 | $ 6,835 | $ 2,016 | $ 622
Gain (loss) on sale of real estate, net | $ | $ 1 | $ (1,800) |  | $ 3,993 | $ 242 | $ 1,538
Discontinued Operations, Held-for-sale or Disposed of by Sale [Member] |  |  |  |  |  |
Schedule Of Real Estate Owned Held For Sale [Line Items] |  |  |  |  |  |
Number of real estates properties classified as held for sale during period |  |  |  | 2 |  |
Held-for-sale |  |  |  |  |  |
Schedule Of Real Estate Owned Held For Sale [Line Items] |  |  |  |  |  |
Impairment charge | $ |  |  |  | $ 3,100 |  |
Number of impaired assets classified as held for sale during period |  |  |  | 2 | 1 | 1
Number of impaired Assets |  |  |  |  | 7 |
Number of impaired assets sold |  |  |  |  | 5 |

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- Definition Number of Impaired Assets, Held and Used + References No definition available. + Details
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- Definition Number of Impaired Assets Sold + References No definition available. + Details
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- Definition Number of Real Estates Properties Classified as Held For Sale During Period + References No definition available. + Details
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- Definition Number of impaired Assets + References No definition available. + Details
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- Definition Schedule of real estate owned held for sale line items. + References No definition available. + Details
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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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2420-110228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 + Details
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- Definition The difference between the carrying value and the sale price of real estate or properties that were intended to be sold or held for capital appreciation or rental income. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 + Details
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