Consolidated Statements of Changes in Stockholders' Equity - 6 months ended Jun. 30, 2015 - 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, 2014	$ 334,208	$ 120	$ 307,059	$ (70,247)	$ 101,813	$ (4,537)
Net income	48,831				48,831
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	(316)					(316)
Unrealized net gain on securities available-for-sale, net of tax	(6)					(6)
Stock-based compensation	6,025		6,025
Exercise of stock options	990		990
Withholding tax payments on restricted stock vesting and stock option exercises	(4,243)		(4,243)
Excess tax benefits from stock-based compensation	3,755		3,755
Repurchases of common stock	(14,464)			(14,464)
Cash dividend on common stock	(14,923)				(14,923)
Ending Balance at Jun. 30, 2015	$ 359,857	$ 120	$ 313,586	$ (84,711)	$ 135,721	$ (4,859)