Cumulative Other Comprehensive Income (Loss) (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Reclassifications out of cumulative other comprehensive income (Loss)
Interest expenses	$ 37,899	$ 43,320	$ 75,834	$ 95,216
Equity in earnings of investees	(12,454)	(159)	(23,388)	(4,421)
Loss (gain) on sale of equity investments	33		33	(66,293)
Total reclassifications	(1,175)		(2,397)
Cumulative Other Comprehensive Income (Loss) to Net Income
Reclassifications out of cumulative other comprehensive income (Loss)
Total reclassifications	1,175		2,397
Unrealized gains and losses on available for sale securities
Reclassifications out of cumulative other comprehensive income (Loss)
Total reclassifications	84		91
Unrealized gains and losses on available for sale securities | Cumulative Other Comprehensive Income (Loss) to Net Income
Reclassifications out of cumulative other comprehensive income (Loss)
Equity in earnings of investees	(7)		(14)
Loss (gain) on sale of equity investments	(77)		(77)
Interest rate swap contracts | Cumulative Other Comprehensive Income (Loss) to Net Income
Reclassifications out of cumulative other comprehensive income (Loss)
Interest expenses	$ 1,259		$ 2,488