Consolidated Statement of Stockholders' Equity - 9 months ended Sep. 30, 2015 - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]
Beginning Balance at Dec. 31, 2014	$ 476,232	$ 497	$ (53,770)	$ 158,549	$ (35)	$ 370,991
Beginning Balance, Shares at Dec. 31, 2014		49,746	3,002
Comprehensive income	92,878				(419)	93,297
Restricted shares forfeited	0	$ 0	$ 0	0	0	0
Restricted shares forfeited, Shares			15
Exercise of stock options	2,871	$ 2		2,869
Exercise of stock options, Shares		177
Excess tax benefits	3,515			3,515
Share-based compensation	4,141	$ 3	$ (4,230)	8,368
Share-based compensation, Shares		324	92
Ending Balance at Sep. 30, 2015	$ 579,637	$ 502	$ (58,000)	$ 173,301	$ (454)	$ 464,288
Ending Balance, Shares at Sep. 30, 2015		50,247	3,109