CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2012	$ 1,940,291	$ 932	$ 927,368	$ 1,039,491	$ (36,151)	$ 8,651
Beginning balance, shares at Dec. 31, 2012		93,202			536
Treasury shares acquired	$ (116,132)				$ (116,132)
Treasury shares acquired, shares	1,494				1,494
Stock-based compensation activity, including tax benefit	$ 78,055		(1,337)		$ 79,392
Stock-based compensation activity, including tax benefit, shares		(34)			(1,112)
Other comprehensive loss	(11,295)					(11,295)
Net income for the year	245,327			245,327
Ending balance at Dec. 31, 2013	2,136,246	$ 932	926,031	1,284,818	$ (72,891)	(2,644)
Ending balance, shares at Dec. 31, 2013		93,236			918
Treasury shares acquired	$ (233,793)				$ (233,793)
Treasury shares acquired, shares	2,977				2,977
Stock-based compensation activity, including tax benefit	$ 90,046		(20,628)		$ 110,674
Stock-based compensation activity, including tax benefit, shares					(1,424)
Other comprehensive loss	(29,110)					(29,110)
Net income for the year	254,690			254,690
Acquisition-related activity	(578)		(578)
Ending balance at Dec. 31, 2014	2,217,501	$ 932	904,825	1,539,508	$ (196,010)	(31,754)
Ending balance, shares at Dec. 31, 2014		93,236			2,471
Treasury shares acquired	$ (337,910)				$ (337,910)
Treasury shares acquired, shares	3,833				3,833
Stock-based compensation activity, including tax benefit	$ 79,197		(8,434)		$ 87,631
Stock-based compensation activity, including tax benefit, shares					(1,139)
Other comprehensive loss	(20,410)					(20,410)
Net income for the year	252,521			252,521
Acquisition-related activity	3,528		(1,922)		$ 5,450
Acquisition-related activity, shares					(68)
Ending balance at Dec. 31, 2015	$ 2,194,427	$ 932	$ 894,469	$ 1,792,029	$ (440,839)	$ (52,164)
Ending balance, shares at Dec. 31, 2015		93,236			5,097