Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data	Total	Common Stock	Treasury Stock	Additional Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2011	$ 215,084	$ 28	$ (1,116)	$ 110,163	$ 106,203	$ (194)
Beginning Balance (in shares) at Dec. 31, 2011		27,894,543	58,730
Stock-Based Compensation Expense	3,977	0	0	3,977	0	0
Exercise of Stock Options (in shares)		937,048	0
Exercise of Stock Options	10,454	1	0	10,453	0	0
Excess Tax Benefits on Stock Option Exercises	7,131	0	0	7,131	0	0
Release of Restricted Shares (in shares)		43,529	0
Release of Restricted Shares	0	0	0	0	0	0
Common Stock Repurchased (in shares)		(1,660,976)	1,660,976
Common Stock Repurchased	(49,436)	0	(49,436)	0	0	0
Translation Adjustment	267	0	0	0	0	267
Net Income	47,064	0	0	0	47,064	0
Ending Balance at Dec. 31, 2012	234,541	29	(50,552)	131,724	153,267	73
Ending Balance (in shares) at Dec. 31, 2012		27,214,144	1,719,706
Stock-Based Compensation Expense	5,471	0	0	5,471	0	0
Exercise of Stock Options (in shares)		718,665	0
Exercise of Stock Options	10,255	1	0	10,254	0	0
Excess Tax Benefits on Stock Option Exercises	17,132	0	0	17,132	0	0
Release of Restricted Shares (in shares)		38,362	0
Release of Restricted Shares	0	0	0	0	0	0
Common Stock Repurchased (in shares)		(413,601)	413,601
Common Stock Repurchased	(34,830)	0	(34,830)	0	0	0
Translation Adjustment	(635)	0	0	0	0	(635)
Net Income	77,395	0	0	0	77,395	0
Ending Balance at Dec. 31, 2013	309,329	30	(85,382)	164,581	230,662	(562)
Ending Balance (in shares) at Dec. 31, 2013		27,557,570	2,133,307
Stock-Based Compensation Expense	5,744	0	0	5,744	0	0
Exercise of Stock Options (in shares)		149,707	0
Exercise of Stock Options	3,150	0	0	3,150	0	0
Excess Tax Benefits on Stock Option Exercises	4,004	0	0	4,004	0	0
Release of Restricted Shares (in shares)		45,503	0
Release of Restricted Shares	0	0	0	0	0	0
Common Stock Repurchased (in shares)		(683,473)	683,473
Common Stock Repurchased	(53,310)	0	(53,310)	0	0	0
Translation Adjustment	(234)	0	0	0	0	(234)
Net Income	63,371	0	0	0	63,371	0
Ending Balance at Dec. 31, 2014	$ 332,054	$ 30	$ (138,692)	$ 177,479	$ 294,033	$ (796)
Ending Balance (in shares) at Dec. 31, 2014		27,069,307	2,816,780