Indebtedness - Summary of Indebtedness at Estimated Fair Value (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Carrying Amount	[1]	$ 1,353,679	$ 1,442,411
Fair Value		1,384,111	1,495,687
Mortgage Loans Payable
Debt Instrument [Line Items]
Carrying Amount	[1]	498,861	564,955
Fair Value		513,540	595,964
Senior Unsecured Notes
Debt Instrument [Line Items]
Carrying Amount	[1]	205,318	364,956
Fair Value		222,469	386,253
Unsecured Term Loans
Debt Instrument [Line Items]
Carrying Amount	[1]	460,000	460,000
Fair Value		458,602	460,970
Unsecured Credit Facility
Debt Instrument [Line Items]
Carrying Amount	[1]	189,500	52,500
Fair Value		$ 189,500	$ 52,500

[1] The carrying amounts include unamortized premiums and discounts and exclude unamortized deferred financing costs.