Consolidated Statement Of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Available-for-sale-securities [Member]	Foreign Currency Translation [Member]	Total
Balance at Dec. 31, 2013	$ 352	$ 919,840	$ (660,421)	$ 1,276,897		$ 1,620	$ 1,538,288
Balance, Shares at Dec. 31, 2013	35,245		4,212
Stock-based compensation		97,618					97,618
Stock plan transactions and other	$ 2	(193)					(191)
Stock plan transactions and other, Shares	149
Excess tax benefit on stock-based compensation		21,667					21,667
Acquisition of treasury stock (value)			$ (88,338)				(88,338)
Acquisition of treasury stock (shares)			155
Net income				445,374			445,374
Other Comprehensive Income (Loss), Net of Income Tax						(2,049)	(2,049)
Balance at Dec. 31, 2014	$ 354	1,038,932	$ (748,759)	1,722,271		(429)	2,012,369
Balance, Shares at Dec. 31, 2014	35,394		4,367
Stock-based compensation		59,465					59,465
Stock plan transactions and other	$ 4	(211)					(207)
Stock plan transactions and other, Shares	396
Excess tax benefit on stock-based compensation		74,442					74,442
Acquisition of treasury stock (value)			$ (485,853)				(485,853)
Acquisition of treasury stock (shares)			839
Net income				475,602			475,602
Other Comprehensive Income (Loss), Net of Income Tax					$ (1,522)	(6,322)	(7,844)
Balance at Dec. 31, 2015	$ 358	1,172,628	$ (1,234,612)	2,197,873	(1,522)	(6,751)	2,127,974
Balance, Shares at Dec. 31, 2015	35,790		5,206
Stock-based compensation		65,112					65,112
Stock plan transactions and other		(185)					(185)
Stock plan transactions and other, Shares	43
Excess tax benefit on stock-based compensation		1,320					1,320
Acquisition of treasury stock (value)			$ (814,777)				$ (814,777)
Acquisition of treasury stock (shares)			1,813				1,811
Net income				22,938			$ 22,938
Other Comprehensive Income (Loss), Net of Income Tax					1,402	(1,291)	111
Balance at Dec. 31, 2016	$ 358	$ 1,238,875	$ (2,049,389)	$ 2,220,811	$ (120)	$ (8,042)	$ 1,402,493
Balance, Shares at Dec. 31, 2016	35,833		7,019