Quarterly Results (Details) (USD $) In Thousands, except Per Share data, 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
Quarterly Results [Abstract]
Revenue	$ 1,055,800	$ 908,300	$ 671,300	$ 541,300	$ 579,200	$ 519,700	$ 577,200	$ 456,200	$ 3,176,718	$ 2,132,257	$ 1,719,588
Gross profit	891,100	768,500	560,000	451,300	484,100	433,000	481,600	380,400	2,670,912	1,779,105	1,396,964
Operating income	188,600	168,300	114,600	82,600	88,900	82,400	97,900	71,600	554,112	340,844	233,742
Net income	$ 125,300	$ 110,900	$ 74,400	$ 54,300	$ 59,200	$ 54,200	$ 60,400	$ 47,800	$ 364,888	$ 221,645	$ 153,330
Net income per share:
Basic (in dollars per share)	$ 2.13	$ 1.89	$ 1.27	$ 0.93	$ 1.01	$ 0.90	$ 0.98	$ 0.77	$ 6.23	$ 3.66	$ 2.47
Diluted (in dollars per share)	$ 2.02	$ 1.80	$ 1.22	$ 0.90	$ 0.97	$ 0.87	$ 0.94	$ 0.74	$ 5.94	$ 3.52	$ 2.38