Income Taxes Provision For Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current tax expense [Abstract]
Federal		$ 41,010	$ 40,642	$ 48,494
State		4,713	2,629	3,609
Foreign	(4,500)	2,345	1,712	1,892
Deferred tax expense [Abstract]
Federal		366	2,151	(3,264)
State		75	544	310
Foreign		(28)	(17)	(271)
Income taxes		$ 48,481	$ 47,661	$ 50,770