Other Assets and Other Liabilities (Deferred Expenses and Other Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2018	Dec. 31, 2015
Real Estate Properties [Line Items]
Intangible assets, net	$ 156,281	$ 27,124
Other receivables	46,887	56,369
Restricted cash	42,793	20,045	$ 25,883		$ 26,657
Other assets	32,333	23,081
Leasing costs, net	6,224	9,050
Corporate furniture, fixtures and equipment, net	3,850	4,652
Deferred financing fees, net	900	1,409
Deferred expenses and other assets, net	289,268	141,730
Intangible assets, accumulated amortization	27,000	34,900
Amortization of above market lease and lease incentives	2,200	2,500	3,900
Amortization of intangible assets	$ 7,200	1,900	$ 1,900
Weighted average useful life	22 years 3 months 19 days
Accumulated amortization on leasing costs	$ 4,400	4,700
Accumulated depreciation on corporate furniture, fixtures and equipment	11,900	10,500
Net Lease Venture
Real Estate Properties [Line Items]
Intangible assets, net				$ 135,300
Operating Properties
Real Estate Properties [Line Items]
Other receivables	$ 26,000	$ 26,000