Segment Information - Reconciliation of Consolidated NOI to Consolidated Net Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting [Abstract]
Consolidated net operating income	$ 79,839	$ 81,727
Less:
Interest expense	(21,437)	(23,691)
Interest expense - amortization of deferred financing costs	(634)	(774)
Interest expense - financing obligation	0	(281)
Depreciation and amortization	(45,892)	(48,873)
General and administrative expenses	(9,425)	(9,120)
Equity in loss of Real Estate Ventures	(748)	(403)
Provision for impairment	(2,730)	(7,390)
Loss on early extinguishment of debt	0	(66,590)
Plus:
Interest income	393	320
Net gain on disposition of real estate	7,323	115,456
Net gain on Real Estate Venture transactions	14,582	5,929
Net income	$ 21,271	$ 46,310