Reportable Business Segments (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income	$ 206,176	$ 214,874	$ 391,455	$ 400,959
Interest expense	(15,099)	(11,371)	(28,848)	(21,387)
Stock-based compensation expense	(7,610)	(7,061)	(15,101)	(13,381)
Change in contingent acquisition related obligations		17,813		17,813
Income before income taxes	193,711	205,633	367,428	383,406
Total
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income	223,044	212,880	424,579	414,451
Unallocated amount to segment
Reconciliation of segment operating income to consolidated income before income taxes
Interest expense	(15,099)	(11,371)	(28,848)	(21,387)
Interest Income	2,990	2,311	5,530	4,129
Stock-based compensation expense	(7,610)	(7,061)	(15,101)	(13,381)
Change in contingent acquisition related obligations		17,813		17,813
Other costs, net	$ (9,614)	$ (8,939)	$ (18,732)	$ (18,219)