Indebtedness - Summary of Indebtedness at Estimated Fair Value (Details) - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Mortgage Loans Payable, Net		$ 146,770	$ 148,770
Senior Unsecured Notes, Net		1,069,826	1,096,262
Unsecured Term Loans		460,946	458,207
Total		1,677,542	1,703,239
Carrying Amount (A)
Debt Instrument [Line Items]
Mortgage Loans Payable, Net	[1]	142,941	144,214
Senior Unsecured Notes, Net	[1]	998,508	998,506
Unsecured Term Loans	[1]	460,000	460,000
Total	[1]	$ 1,601,449	$ 1,602,720

[1] The carrying amounts include unamortized premiums and discounts and exclude unamortized debt issuance costs.