Operating Segments and Concentrations of Credit Risk (Geographic Information) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net revenues	$ 519,471	$ 513,883	$ 500,336	$ 499,039	$ 496,314	$ 481,890	$ 456,127	$ 444,327	$ 2,032,729	$ 1,878,658	$ 1,685,407
Total long-lived assets	9,074,799				9,236,876				9,074,799	9,236,876
United States [Member]
Net revenues									1,902,536	1,772,793	1,597,790
United States long-lived assets	8,847,161				8,997,016				8,847,161	8,997,016
Australia [Member]
Net revenues									126,214	102,416	84,310
Foreign countries long-lived assets	212,067				222,938				212,067	222,938
Other Countries [Member]
Net revenues									3,979	3,449	3,307
Foreign countries long-lived assets	$ 15,571				$ 16,922				$ 15,571	$ 16,922