Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
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
Other comprehensive income	(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		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
Other comprehensive income	(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	138,415,000	138,415,000
Restricted stock issued, net		$ 16	(16)
Restricted stock issued net, shares		1,662,000
Shares repurchased	$ (39,379)	$ (37)	(39,342)
Shares repurchased, shares		(3,778,000)
Exercise of stock options, net	$ 195	$ 2	193
Exercise of stock options net, shares	176,350	176,000
Stock-based compensation	$ 14,892		14,892
Tax benefit from stock option exercised and vested restricted shares	8,557		8,557
Other comprehensive income	82			82
Dividends	(43,660)		(17,505)		(26,155)
Net income	26,155				26,155
Balance at Dec. 31, 2016	$ 201,344	$ 1,365	$ 224,739	$ (44)	$ (24,716)
Balance, shares at Dec. 31, 2016	136,475,000	136,475,000