Segment Information (Details 2) (USD $) In Thousands, unless otherwise specified	0 Months Ended	3 Months Ended		6 Months Ended
	Jun. 27, 2014	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Information
Rental income		$ 172,407	$ 210,013	$ 344,447	$ 421,313
Tenant reimbursements and other income		42,787	52,175	88,007	103,487
Operating expenses		(92,701)	(104,105)	(194,432)	(208,235)
NOI		122,493	158,083	238,022	316,565
Reconciliation of NOI to net income
NOI		122,493	158,083	238,022	316,565
Depreciation and amortization		(59,831)	(63,459)	(111,480)	(126,029)
General and administrative		(24,097)	(21,049)	(48,945)	(37,712)
Loss on asset impairment		(22,683)		(17,922)
Acquisition related costs			(145)	(5)	(773)
Operating income		15,882	73,430	59,670	152,051
Interest and other income		281	249	665	704
Interest expense		(37,899)	(43,320)	(75,834)	(95,216)
Loss on early extinguishment of debt					(60,027)
(Loss) gain on sale of equity investments		(33)		(33)	66,293
Gain on issuance of shares by an equity investee		16,911		17,020
(Loss) income from continuing operations before income tax expense and equity in earnings of investees		(4,858)	30,359	1,488	63,805
Income tax expense		(908)	(754)	(1,463)	(1,742)
Equity in earnings of investees		12,454	159	23,388	4,421
Income from continuing operations		6,688	29,764	23,413	66,484
Income from discontinued operations		4,114	1,643	8,125	1,637
Loss on asset impairment from discontinued operations	2,400	(2,072)	(4,589)	(2,360)	(8,535)
Loss on early extinguishment of debt from discontinued operations	3,300	(3,345)		(3,345)
Net gain on sale of properties from discontinued operations			2,099		3,359
Income before gain on sale of properties		5,385	28,917	25,833	62,945
Gain on sale of properties					1,596
Net income		$ 5,385	$ 28,917	$ 25,833	$ 64,541