Consolidated Statements of Changes in Stockholders' Equity - 9 months ended Sep. 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	71,546				71,546
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	(420)					(420)
Unrealized net loss on securities available-for-sale, net of tax	(12)					(12)
Stock-based compensation	9,276		9,276
Exercise of stock options	1,530		1,530
Withholding tax payments on restricted stock vesting and stock option exercises	(4,450)		(4,450)
Excess tax benefits from stock-based compensation	4,202		4,202
Repurchases of common stock	(20,025)			(20,025)
Cash dividend on common stock	(22,384)				(22,384)
Ending Balance at Sep. 30, 2015	$ 373,471	$ 120	$ 317,617	$ (90,272)	$ 150,975	$ (4,969)