Investments in Unconsolidated Joint Ventures - Summary of Financial Information (Details) - 712 Fifth Avenue [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Schedule Of Equity Method Investments [Line Items]
Rental property, net	$ 206,700		$ 207,632
Other assets	46,173		40,701
Total assets	252,873		248,333
Notes and mortgages payable, net	246,092		245,990
Other liabilities	9,361		8,783
Total liabilities	255,453		254,773
Equity	(2,580)		(6,440)
Total liabilities and equity	252,873		$ 248,333
Rental income	12,945	$ 12,678
Tenant reimbursement income	1,308	1,116
Fee and other income	126	518
Total revenues	14,379	14,312
Operating expenses	5,966	5,617
Depreciation and amortization	2,920	3,008
Total expenses	8,886	8,625
Operating income	5,493	5,687
Interest and other income, net	24	14
Interest and debt expense	(2,825)	(2,748)
Unrealized gain on interest rate swaps	1,168
Net income	$ 3,860	$ 2,953