Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Comprehensive Loss [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2012	$ 51,060	$ 1,265	$ 177,826		$ (128,031)
Balance, shares at Dec. 31, 2012		126,554,000
Restricted stock issued, net		$ 10	(10)
Restricted stock issued net, shares		974,000
Shares repurchased	(1,613)	$ (1)	(1,612)
Shares repurchased, shares		(137,000)
Exercise of stock options, net	$ 1,586	$ 48	1,538
Exercise of stock options net, shares	4,875,500	4,856,000
Stock-based compensation	$ 6,459		6,459
Net income	51,537				51,537
Balance at Dec. 31, 2013	109,029	$ 1,322	184,201		(76,494)
Balance, shares at Dec. 31, 2013		132,247,000
Restricted stock issued, net		$ 6	(6)
Restricted stock issued net, shares		613,000
Shares repurchased	(6,531)	$ (4)	(6,527)
Shares repurchased, shares		(416,000)
Exercise of stock options, net	$ 1,544	$ 26	1,518
Exercise of stock options net, shares	2,514,621	2,515,000
Stock-based compensation	$ 8,137		8,137
Tax benefit from stock option exercised and vested restricted shares	21,893		21,893
Foreign currency translation adjustment	(53)			$ (53)
Dividends	(10,785)				(10,785)
Net income	61,051				61,051
Balance at Dec. 31, 2014	$ 184,285	$ 1,350	209,216	(53)	(26,228)
Balance, shares at Dec. 31, 2014	133,445,000	134,959,000
Restricted stock issued, net		$ 9	(9)
Restricted stock issued net, shares		861,000
Shares repurchased	$ (24,116)	$ (12)	(24,104)
Shares repurchased, shares		(1,190,000)
Exercise of stock options, net	$ 4,520	$ 37	4,483
Exercise of stock options net, shares	3,785,473	3,785,000
Stock-based compensation	$ 10,900		10,900
Tax benefit from stock option exercised and vested restricted shares	57,474		57,474
Foreign currency translation adjustment	(73)			(73)
Dividends	(78,540)				(78,540)
Net income	80,052				80,052
Balance at Dec. 31, 2015	$ 234,502	$ 1,384	$ 257,960	$ (126)	$ (24,716)
Balance, shares at Dec. 31, 2015	136,794,000	138,415,000