Cumulative Other Comprehensive (Loss) Income (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Amounts Reclassified from AOCI
Interest expenses	$ 43,762	$ 50,237	$ 96,106	$ 99,343
Equity in earnings of investees	(159)	(2,829)	(4,421)	(5,787)
Net of tax	28,917	20,586	64,541	45,160
Amount Reclassified from Cumulated Other Comprehensive Income (Loss) to Net Income
Amounts Reclassified from AOCI
Net of tax	1,232		2,455
Unrealized net losses on Available-for-Sale securities | Amount Reclassified from Cumulated Other Comprehensive Income (Loss) to Net Income
Amounts Reclassified from AOCI
Equity in earnings of investees	(4)		(17)
Interest rate swap contracts | Amount Reclassified from Cumulated Other Comprehensive Income (Loss) to Net Income
Amounts Reclassified from AOCI
Interest expenses	$ 1,236		$ 2,472