Reportable Business Segments (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income	$ 267,821	$ 224,483	$ 755,766	$ 655,453
Interest expense	(21,089)	(16,048)	(60,241)	(47,126)
Stock-based compensation expense	(10,133)	(9,413)	(29,382)	(19,432)
Acquisition-related expenses	(2,547)	(2,537)	(4,567)	(2,537)
Income before income taxes	251,478	212,060	708,629	617,770
Operating Segment
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income	291,085	245,824	820,382	713,250
Unallocated amount to segment
Reconciliation of segment operating income to consolidated income before income taxes
Interest expense	21,089	16,048	60,241	47,126
Interest Income	5,383	4,142	14,553	10,628
Stock-based compensation expense	10,133	9,413	29,382	26,584
Acquisition-related expenses	2,547	2,537	4,567	2,537
Other costs, net	11,221	9,908	32,116	29,861
Income before income taxes	$ 251,478	$ 212,060	$ 708,629	$ 617,770