Investment in Unconsolidated Joint Venture (Condensed Balance Sheet) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014	Oct. 30, 2013
Schedule of Equity Method Investments [Line Items]
Real estate assets, at cost	$ 1,824,272	$ 1,822,903
Less accumulated depreciation and amortization	(198,778)	(172,668)
Total real estate investments, net	1,625,494	1,650,235
Cash and cash equivalents	88,130	98,604	$ 27,486	$ 22,512
Total assets	1,986,445	2,064,762
Total liabilities	954,421	972,493
Deficit	(418,197)	(369,273)
Total liabilities and equity	1,986,445	2,064,762
Company's basis	201,114	215,370
Worldwide Plaza
Schedule of Equity Method Investments [Line Items]
Real estate assets, at cost	715,266	714,642
Less accumulated depreciation and amortization	(127,218)	(117,092)
Total real estate investments, net	588,048	597,550
Cash and cash equivalents	3,935	9,036
Other assets	267,127	259,894
Total assets	859,110	866,480
Debt	875,000	875,000			$ 875,000
Other liabilities	16,914	15,515
Total liabilities	891,914	890,515
Deficit	(32,804)	(24,035)
Total liabilities and equity	859,110	866,480
Company's basis	$ 201,114	$ 215,370