Cumulative Other Comprehensive Income (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Amounts Reclassified from AOCI
Interest expenses	$ 52,344	$ 49,106
Equity in earnings of investees	(4,262)	(2,958)
Net of tax	35,624	24,574
Amount Reclassified from Cumulated Other Comprehensive Income (Loss) to Net Income
Amounts Reclassified from AOCI
Net of tax	1,223
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	13
Interest rate swap contracts | Amount Reclassified from Cumulated Other Comprehensive Income (Loss) to Net Income
Amounts Reclassified from AOCI
Interest expenses	$ 1,236