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Real Estate Dispositions, Held for Sale, and Impairment Charges - Additional Information (Detail) $ in Thousands | 12 Months Ended
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Dec. 31, 2016 USD ($) property | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($)
Schedule Of Real Estate Owned Held For Sale [Line Items] |  |  |
Number of properties sold | 6 |  |
Number of impaired assets, held and used | 0 |  |
Impairment charge | $ | $ 2,016 | $ 622 | $ 14,238
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 | 10 |  |
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 |  |
Number of properties sold | 6 |  |
Number of real estate properties, held for sale | 2 |  |
Number of impaired assets sold, held and used | 1 |  |
Held-for-sale [Member] |  |  |
Schedule Of Real Estate Owned Held For Sale [Line Items] |  |  |
Number of impaired assets classified as held for sale during period | 7 |  |
Number of impaired assets sold | 5 |  |
Number of impaired assets sold, held for sale | 1 |  |
Angola, Indiana [Member] |  |  |
Schedule Of Real Estate Owned Held For Sale [Line Items] |  |  |
Number of properties sold | 2 |  |

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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=51824106&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=56944662&loc=d3e3602-108585 + Details
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