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Mortgage Notes Payable, Revolving Credit Facility, and Term Loan Facility - Mortgage Notes Payable (Details) - USD ($) $ in Thousands |  | 12 Months Ended
--- | --- | ---
Oct. 27, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Debt Instrument [Line Items] |  |  |  |
Debt repaid |  | $ 60,080 | $ 88,899 | $ 66,714
Weighted average interest rate on debt outstanding (as percent) |  | 4.42% |  |
Proceeds from debt issuance |  | $ 51,208 | $ 78,705 | $ 68,499
Fixed rate mortgage loans |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt repaid |  | $ 41,077 |  |
Weighted average interest rate on debt outstanding (as percent) |  | 6.25% |  |
Variable rate mortgage loans |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt repaid |  | $ 8,163 |  |
New Fixed Rate Mortgage Notes Payable |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Weighted average interest rate on debt outstanding (as percent) |  | 3.78% |  |
Proceeds from debt issuance |  | $ 54,887 |  |
New Variable Rate Mortgage Notes Payable |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Proceeds from debt issuance |  | $ 7,500 |  |
London Interbank Offered Rate (LIBOR) |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Libor rate (as percent) | 2.75% | 1.56% |  |
London Interbank Offered Rate (LIBOR) | Variable rate mortgage loans | Weighted Average |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Libor rate (as percent) |  | 2.50% |  |

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- Definition The cash inflow from a borrowing supported by a written promise to pay an obligation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3255-108585 + Details
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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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