Segment Information - Reconciliation of Consolidated Net Income to Consolidated NOI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting [Abstract]
Net income	$ 44,705	$ 21,271
Plus:
Interest expense	19,533	21,437
Interest expense - amortization of deferred financing costs	627	634
Depreciation and amortization	43,291	45,892
General and administrative expenses	8,723	9,325
Equity in loss of Real Estate Ventures	825	748
Provision for impairment	0	2,730
Less:
Interest income	703	393
Income tax provision	(138)	(100)
Net gain on disposition of real estate	0	7,323
Net gain on sale of undepreciated real estate	22	0
Net gain on Real Estate Venture transactions	37,263	14,582
Consolidated net operating income	$ 79,854	$ 79,839