Investment in Unconsolidated Real Estate Ventures - Aggregate Principal Payments of Recourse and Non-recourse Debt Payable to Third-parties (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Equity Method Investments [Line Items]
2018	$ 6,601
2019	7,360
2020	86,978
2021	6,099
2022	256,332
Thereafter	1,585,347
Total principal payments	768,912	$ 997,466
Net deferred financing costs	(11,141)
Outstanding indebtedness	766,420	$ 989,738
Unconsolidated Real Estate Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
2018	236,468
2019	390,707
2020	92,679
2021	17,162
2022	25,372
Thereafter	6,524
Total principal payments	768,912
Net deferred financing costs	(2,532)
Outstanding indebtedness	$ 766,380