Indebtedness - Summary of Indebtedness at Estimated Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Carrying Amount (A)
Debt Instrument [Line Items]
Mortgage Loans Payable, Net	$ 297,716	$ 451,862
Senior Unsecured Notes, Net	548,494	248,487
Unsecured Term Loans	460,000	460,000
Unsecured Credit Facility	0	144,500
Total	1,306,210	1,304,849
Fair Value
Debt Instrument [Line Items]
Mortgage Loans Payable, Net	304,508	467,303
Senior Unsecured Notes, Net	546,607	269,731
Unsecured Term Loans	461,317	460,000
Unsecured Credit Facility	0	144,500
Total	$ 1,312,432	$ 1,341,534

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

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Fair value portion of notes payable.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20,22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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