Segment Information - Schedule of Reconciliation of NOI to Net Income (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting [Abstract]
Rental income		$ 691,699	$ 763,262	$ 774,600
Tenant reimbursements and other income		170,158	189,767	186,487
Operating expenses		(387,982)	(410,045)	(397,673)
NOI		473,875	542,984	563,414
Depreciation and amortization		(227,532)	(234,402)	(230,284)
General and administrative		(113,155)	(80,504)	(49,312)
Loss on asset impairment		(185,067)	(124,253)	0
Acquisition related costs		(5)	(318)	(5,648)
Operating (loss) income		(51,884)	103,507	278,170
Interest and other income		1,561	1,229	1,410
Interest expense		(143,230)	(173,011)	(202,055)
Gain (loss) on early extinguishment of debt	(60,000)	4,909	(60,052)	(287)
Gain on sale of equity investment		171,561	66,293	0
Gain on issuance of shares by an equity investee		17,020	0	7,246
(Loss) income from continuing operations before income tax expense and equity in earnings of investees		(63)	(62,034)	84,484
Income tax expense		(3,191)	(2,634)	(3,207)
Equity in earnings of investees		24,460	25,754	11,420
Income (loss) from continuing operations		21,206	(38,914)	92,697
Income (loss) from discontinued operations		8,389	6,393	(4,341)
Loss on asset impairment from discontinued operations		(2,238)	(102,869)	(168,632)
Loss on early extinguishment of debt from discontinued operations		(3,345)	(1,011)	(1,608)
Net (loss) gain on sale of properties from discontinued operations		0	(22,162)	2,039
Income (loss) before gain on sale of properties		24,012	(158,563)	(79,845)
Gain on sale of properties		0	1,596	0
Net income (loss)		$ 24,012	$ (156,967)	$ (79,845)