Indebtedness - Summary of Indebtedness at Estimated Fair Value (Detail) - USD ($) $ in Thousands		Sep. 30, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Carrying Amount	[1]	$ 1,332,129	$ 1,442,411
Fair Value		1,381,783	1,495,687
Mortgages
Debt Instrument [Line Items]
Carrying Amount	[1]	503,321	564,955
Fair Value		531,215	595,964
Senior Unsecured Notes
Debt Instrument [Line Items]
Carrying Amount	[1]	205,308	364,956
Fair Value		228,527	386,253
Unsecured Term Loan
Debt Instrument [Line Items]
Carrying Amount	[1]	460,000	460,000
Fair Value		458,541	460,970
Unsecured Credit Facility
Debt Instrument [Line Items]
Carrying Amount	[1]	163,500	52,500
Fair Value		$ 163,500	$ 52,500

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