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Subsequent Events Subsequent Events - Mortgage Debt Repayment (Details) - USD ($) $ in Thousands |  | 12 Months Ended
--- | --- | ---
Jan. 23, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Subsequent Event [Line Items] |  |  |  |
Repayments of secured debt |  | $ 60,080 | $ 88,899 | $ 66,714
Variable rate mortgage loans |  |  |  |
Subsequent Event [Line Items] |  |  |  |
Repayments of secured debt |  | $ 8,163 |  |
Variable rate mortgage loans | Subsequent Event |  |  |  |
Subsequent Event [Line Items] |  |  |  |
Repayments of secured debt | $ 6,700 |  |  |

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- Definition The cash outflow to repay long-term debt that is wholly or partially secured by collateral. Excludes repayments of tax exempt secured debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585 + Details
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Balance Type: | credit
Period Type: | duration

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- Definition Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event. + References No definition available. + Details
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Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
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Balance Type: |
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