Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning Balance at Dec. 31, 2014	$ 401,407	$ 510	$ 882,193	$ (8,002)	$ (446,963)	$ (26,331)
Net income	111,511				111,511
Other comprehensive income (loss), net of income taxes	1,284					1,284
Payment of dividend	(139,041)		910	(1,999)	(137,952)
Exercise of stock options	1,777	1	1,776
Restricted stock units and stock options surrendered	(3,534)	2	(3,536)
Stock-based compensation expense	6,158		6,158
Ending Balance at Dec. 31, 2015	379,562	513	887,501	(10,001)	(473,404)	(25,047)
Net income	159,366				159,366
Other comprehensive income (loss), net of income taxes	2,779					2,779
Repurchase of Company stock for retirement	(24,811)	(5)			(24,806)
Payment of dividend	(153,694)		883	(1,541)	(153,036)
Exercise of stock options	1,702		1,702
Restricted stock units and stock options surrendered	(3,110)	2	(3,112)
Stock-based compensation expense	6,128		6,128
Ending Balance at Dec. 31, 2016	367,997	510	893,102	(11,542)	(491,805)	(22,268)
Tax benefit related to adoption of ASU 2016-09	75				75
Net income	176,100				176,100
Other comprehensive income (loss), net of income taxes	(4,424)					(4,424)
Payment of dividend	(164,431)		745	(1,711)	(163,465)
Exercise of stock options	65		65
Restricted stock units and stock options surrendered	(3,791)	2	(3,793)
Stock-based compensation expense	6,640		6,640
Ending Balance at Dec. 31, 2017	$ 378,156	$ 512	$ 896,759	$ (13,253)	$ (479,170)	$ (26,692)