Reportable Business Segments (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Jun. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income	$ 215,670	$ 186,059		$ 607,125	$ 587,018
Interest expense	(15,166)	(10,498)		(44,014)	(31,885)
Interest Income	2,954	2,871		8,484	7,000
Stock-based compensation expense	(8,066)	(7,630)		(23,167)	(21,011)
Change in contingent acquisition related obligations			17,813		17,813
Casualty loss related to flood		(12,831)			(12,831)
Other costs, net	(9,796)	(9,581)		(28,528)	(27,800)
Income before income taxes	203,140	177,816		570,568	561,222
Total
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income	$ 233,214	$ 215,485		$ 657,793	$ 629,936