Other Assets - Schedule of Other Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Investments in debt securities, net	$ 392,860	$ 378,545
Held for sale assets	309,708	46,814
Derivative instruments (Note 7)	157,392	57,612
Investment in unconsolidated joint venture	56,667	57,078
Rent and other receivables, net	36,114	24,525
Prepaid expenses	29,181	37,869
Corporate fixed assets, net	12,254	16,595
Amounts deposited and held by others	7,798	12,598
Deferred leasing costs, net	6,991	7,018
Deferred financing costs, net	5,729	7,504
In-place leases, net	0	37,517
Other	17,755	12,930
Total	$ 1,032,449	$ 696,605