Significant Accounting Policies (Details 3) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Noncontrolling Interests:
Balance			$ 5,951,505
Purchase and disposition of noncontrolling interests, net and other			4,500
Balance	$ 5,120,379		5,120,379
Noncontrolling Interests
Noncontrolling Interests:
Balance	(411)	$ (1,643)	(229)	$ 4,264
Net income attributable to noncontrolling nonredeemable interests	840	750	2,138	1,720
Distributions to noncontrolling nonredeemable interestholders	(781)	(509)	(2,861)	(18,116)
Purchase and disposition of noncontrolling interests, net and other	164	299	764	11,029
Balance	$ (188)	$ (1,103)	$ (188)	$ (1,103)
7.5% Cumulative Redeemable Preferred Units | Noncontrolling Interests
Noncontrolling Interests:
Preferred stock stated dividend rate percentage			7.50%