Indebtedness - Summary of Indebtedness at Estimated Fair Value (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Carrying Amount	[1]	$ 1,377,251	$ 1,353,679
Fair Value		1,406,110	1,384,111
Mortgage Loans Payable
Debt Instrument [Line Items]
Carrying Amount	[1]	459,923	498,861
Fair Value		474,283	513,540
Senior Unsecured Notes
Debt Instrument [Line Items]
Carrying Amount	[1]	205,328	205,318
Fair Value		221,162	222,469
Unsecured Term Loan
Debt Instrument [Line Items]
Carrying Amount	[1]	460,000	460,000
Fair Value		458,665	458,602
Unsecured Credit Facility
Debt Instrument [Line Items]
Carrying Amount	[1]	252,000	189,500
Fair Value		$ 252,000	$ 189,500

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