CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total		Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2014	$ 581,405		$ 698	$ 551,713	$ 331,415	$ (282,538)	$ (19,883)
Net income	85,436				85,436
Other comprehensive income (loss)	(51,693)						(51,693)
Stock-based compensation	18,380			18,380
Shares issued and forfeited, net, under stock plans including income tax benefits	20,142			(14,089)		34,231
Issuance of 476,750 shares under stock plan portion of PAY.ON acquisition agreement			3	(3)
Issuance of 227,917 shares of common stock for acquisition of PAY.ON	5,379		1	5,378
Repurchase of restricted stock and performance shares for tax withholdings	(4,649)					(4,649)
Ending Balance at Dec. 31, 2015	654,400		702	561,379	416,851	(252,956)	(71,576)
Net income	129,535	[1]			129,535
Other comprehensive income (loss)	(22,524)						(22,524)
Stock-based compensation	43,613			43,613
Shares issued and forfeited, net, under stock plans including income tax benefits	13,056			(5,204)		18,260
Repurchase of common stock	(60,089)					(60,089)
Repurchase of restricted stock and performance shares for tax withholdings	(2,975)					(2,975)
Cumulative effect of accounting change, ASU 2016-09	(99)			556	(655)
Ending Balance at Dec. 31, 2016	754,917		702	600,344	545,731	(297,760)	(94,100)
Net income	5,135				5,135
Other comprehensive income (loss)	16,744						16,744
Stock-based compensation	13,683			13,683
Shares issued and forfeited, net, under stock plans including income tax benefits	16,816			(3,682)		20,498
Repurchase of common stock	(37,387)					(37,387)
Repurchase of restricted stock and performance shares for tax withholdings	(5,311)					(5,311)
Ending Balance at Dec. 31, 2017	$ 764,597		$ 702	$ 610,345	$ 550,866	$ (319,960)	$ (77,356)

[1] The Company adopted ASU 2016-09, Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting, ("ASU 2016-09") during the year ended December 31, 2016. The Company elected to early adopt ASU 2016-09 in the third quarter of 2016, which requires it to reflect any adjustments as of January 1, 2016, the beginning of the annual period that includes the interim period of adoption. The impact of the adoption to the Company's previously reported quarterly results for the quarters ended March 31 and June 30, 2016 are reflected in the table above.