Reportable Business Segments and International Operations (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income	$ 241,360	$ 224,483	$ 224,013	$ 206,957	$ 221,220	$ 215,670	$ 206,176	$ 185,279	$ 896,813	$ 828,345	$ 751,678
Interest expense									(63,553)	(59,613)	(43,029)
Interest Income									14,972	11,512	10,245
Stock-based compensation expense									(36,070)	(31,412)	(28,679)
Casualty loss related to flood											(21,479)
Change in contingent acquisition related obligations											17,813
Acquisition-related expenses	(3,400)	(2,500)			(2,000)				(5,983)	(2,000)	(2,000)
Income before income taxes									846,645	778,841	716,752
Segment operating income
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income									977,357	899,205	822,136
Unallocated amount to segment
Reconciliation of segment operating income to consolidated income before income taxes
Interest expense									(63,553)	(59,613)	(43,029)
Interest Income									14,972	11,512	10,245
Stock-based compensation expense									(36,070)	(31,412)	(28,679)
Casualty loss related to flood											(21,479)
Change in contingent acquisition related obligations											17,813
Acquisition-related expenses									(5,983)	(2,000)	(2,000)
Other costs, net									(40,078)	(38,851)	(38,255)
Income before income taxes									$ 846,645	$ 778,841	$ 716,752