Segment Information - Reconciliation of Consolidated NOI to Consolidated Net Income (Loss) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
	Jan. 14, 2016	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting [Abstract]
Consolidated net operating income										$ 316,015	$ 364,544	$ 361,017
Less:
Interest expense										(84,708)	(110,717)	(124,329)
Interest expense - amortization of deferred financing costs										(2,696)	(4,557)	(5,148)
Interest expense - financing obligation										(679)	(1,237)	(1,144)
Depreciation and amortization										(189,676)	(219,029)	(208,569)
General and administrative expenses										(26,596)	(29,406)	(26,779)
Equity in loss of real estate ventures										(11,503)	(811)	(790)
Provision for impairment				$ (1,800)						(40,517)	(82,208)	(1,765)
Plus:
Interest income										1,236	1,224	3,974
Tax credit transaction income										0	19,955	11,853
Recognized hedge activity										0	0	(828)
Net gain from remeasurement of investments in real estate ventures										0	758	458
Net gain on sales of interests in real estate										116,983	20,496	4,901
Net gain on sale of undepreciated real estate										9,232	3,019	1,184
Net gain (loss) on real estate venture transactions										20,000	7,229	(417)
Loss on early extinguishment of debt	$ (66,600)									(66,590)	0	(7,594)
Income (loss) from continuing operations										40,501	(30,740)	6,024
Income from discontinued operations										0	0	918
Net income (loss)		$ (12,370)	$ 7,884	$ (1,323)	$ 46,310	$ (62,700)	$ 20,308	$ 3,058	$ 8,594	$ 40,501	$ (30,740)	$ 6,942