CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury stock.	Total
Balance at Dec. 31, 2013	$ 3,090	$ 366,009	$ 1,847,325	$ (1,233)	$ (1,222,912)	$ 992,279
Balance (in shares) at Dec. 31, 2013	618,042				(117,576)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation		28,989				28,989
Exercise of stock options	$ 15	17,153				17,168
Exercise of stock options (in shares)	2,970
Excess tax benefits from share based payment arrangements		11,924				11,924
Repurchase of common stock					$ (8,175)	(8,175)
Repurchase of common stock (in shares)					(270)
Foreign currency translation				(10,220)		(10,220)
Net income			483,185			483,185
Balance at Dec. 31, 2014	$ 3,105	424,075	2,330,510	(11,453)	$ (1,231,087)	1,515,150
Balance (in shares) at Dec. 31, 2014	621,012				(117,846)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation		32,719				32,719
Exercise of stock options	$ 111	49,217				49,328
Exercise of stock options (in shares)	22,275
Issuance of Common Stock	$ 511	3,168,624				3,169,135
Issuance of common stock (in shares)	102,123
Excess tax benefits from share based payment arrangements		314,737				314,737
Repurchase of common stock					$ (807,967)	$ (807,967)
Repurchase of common stock (in shares)					(18,864)
Cancellation of treasury stock	$ (622)	415	(1,482,380)		$ 1,482,587
Cancellation of treasury stock (in shares)	(124,353)				124,353	(124,500)
Foreign currency translation				(10,425)		$ (10,425)
Net income			546,733			546,733
Balance at Dec. 31, 2015	$ 3,105	3,989,787	1,394,863	(21,878)	$ (556,467)	4,809,410
Balance (in shares) at Dec. 31, 2015	621,057				(12,357)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation		45,848				45,848
Exercise of stock options	$ 11	16,441				16,452
Exercise of stock options (in shares)	2,144
Unrealized loss on available-for-sale securities				(193)		(193)
Excess tax deficiency from share based payment arrangements		(831)				(831)
Repurchase of common stock					$ (2,252,484)	(2,252,484)
Repurchase of common stock (in shares)					(44,278)
Foreign currency translation				(1,178)		(1,178)
Net income			712,685			712,685
Balance at Dec. 31, 2016	$ 3,116	$ 4,051,245	$ 2,107,548	$ (23,249)	$ (2,808,951)	$ 3,329,709
Balance (in shares) at Dec. 31, 2016	623,201				(56,635)