Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss), Net	Accumulated Earnings	Treasury Stock
Beginning Balance at Dec. 31, 2014	$ 161,171	$ 78	$ 764,433	$ (21,170)	$ 1,275,049	$ (1,857,219)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	175,635				175,635
Other comprehensive income (loss)	(23,232)			(23,232)
Issuances under stock plans	7,531		(5,964)			13,495
Stock compensation tax benefits	13,928		13,928
Common share repurchases	(513,582)					(513,582)
Stock compensation expense	46,149		46,149
Ending Balance at Dec. 31, 2015	(132,400)	78	818,546	(44,402)	1,450,684	(2,357,306)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of ASU No. 2016-09	(261)				(261)
Net income	193,582				193,582
Other comprehensive income (loss)	(5,281)			(5,281)
Issuances under stock plans	10,339		(2,080)			12,419
Common share repurchases	(51,762)					(51,762)
Stock compensation expense	46,661		46,661
Ending Balance at Dec. 31, 2016	60,878	78	863,127	(49,683)	1,644,005	(2,396,649)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,279				3,279
Other comprehensive income (loss)	51,191			51,191
Issuances under stock plans and for acquisition	830,446	4	819,313			11,129
Common share repurchases	(41,272)					(41,272)
Stock compensation expense	78,943		78,943
Ending Balance at Dec. 31, 2017	$ 983,465	$ 82	$ 1,761,383	$ 1,508	$ 1,647,284	$ (2,426,792)