Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock Voting [Member]	Additional Paid-in Capital [Member]	Treasury Stock - Common Stock Voting [Member]	Retained Earnings (Deficit) [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning Balance at Dec. 31, 2013	$ 310,362	$ 119	$ 295,557	$ (32,273)	$ 51,042	$ (4,083)
Net income	74,806				74,806
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	(399)					(399)
Unrealized net gain (loss) on securities available-for-sale, net of tax	(55)					(55)
Stock-based compensation	9,769		9,769
Exercise of stock options	2,511	1	2,510
Withholding tax payments on restricted stock vesting and stock option exercises	(5,020)		(5,020)
Excess tax benefits from stock-based compensation	4,243		4,243
Repurchases of common stock	(37,974)			(37,974)
Cash dividend on common stock	(24,035)				(24,035)
Ending Balance at Dec. 31, 2014	334,208	120	307,059	(70,247)	101,813	(4,537)
Net income	96,037				96,037
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	(512)					(512)
Unrealized net gain (loss) on securities available-for-sale, net of tax	(180)					(180)
Stock-based compensation	12,519		12,519
Exercise of stock options	1,824	1	1,823
Withholding tax payments on restricted stock vesting and stock option exercises	(4,496)		(4,496)
Excess tax benefits from stock-based compensation	4,310		4,310
Repurchases of common stock	(23,158)			(23,158)
Cash dividend on common stock	(29,839)				(29,839)
Ending Balance at Dec. 31, 2015	390,713	121	321,215	(93,405)	168,011	(5,229)
Net income	126,172				126,172
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	(7,037)					(7,037)
Unrealized net gain (loss) on securities available-for-sale, net of tax	38					38
Stock-based compensation	14,511		14,511
Exercise of stock options	2,299		2,299
Withholding tax payments on restricted stock vesting and stock option exercises	(5,173)	(1)	(5,172)
Excess tax benefits from stock-based compensation	9,458		9,458
Repurchases of common stock	(23,925)			(23,925)
Cash dividend on common stock	(39,043)				(39,043)
Ending Balance at Dec. 31, 2016	$ 468,013	$ 120	$ 342,311	$ (117,330)	$ 255,140	$ (12,228)