Segment Reporting (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Geographic Information
Long-lived assets	$ 4,030,416				$ 3,922,826				$ 4,030,416	$ 3,922,826
Revenue	786,199	764,721	806,004	764,780	834,209	863,163	584,233	479,826	3,121,704	2,761,431	2,350,369
United States
Geographic Information
Long-lived assets	3,921,385				3,888,283				3,921,385	3,888,283
Revenue									2,403,976	2,229,498	2,010,679
Other
Geographic Information
Long-lived assets	40				3				40	3
Revenue									360,590	316,060	292,222
All other
Geographic Information
Long-lived assets	108,991				34,540				108,991	34,540
Revenue									$ 357,138	$ 215,873	$ 47,468