Reportable Business Segments and International Operations (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended			12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income				$ 716,752	$ 663,688	$ 446,527
Interest expense				(43,029)	(40,741)	(36,586)
Early extinguishment of interest rate swaps						4,575
Stock-based compensation expense				(28,679)	(25,385)	(20,240)
Casualty loss related to flood	8,600	12,800		21,479
Change in contingent acquisition-related obligations			17,800	17,813
Acquisition-related expenses	(2,000)			(2,000)
Total
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income				822,136	761,418	544,523
Unallocated amount to segment
Reconciliation of segment operating income to consolidated income before income taxes
Interest expense				(43,029)	(40,741)	(36,586)
Interest Income				10,245	5,046	2,154
Early extinguishment of interest rate swaps						(4,575)
Stock-based compensation expense				(28,679)	(25,385)	(20,240)
Casualty loss related to flood				(21,479)
Change in contingent acquisition-related obligations				17,813
Acquisition-related expenses				(2,000)
Other costs, net				$ (38,255)	$ (36,650)	$ (38,749)