Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data	Total	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]
Balance - beginning of year at Dec. 31, 2009	$ 147,143	$ 118,576	$ 153	$ 1,873	$ 0	$ 26,541
Balance - beginning of year (in shares) at Dec. 31, 2009				28,097,279	0
Net earnings	33,277	33,277	0	0	0	0
Other comprehensive income (loss)	(702)	0	(702)	0	0	0
Dividends	(4,311)	(4,311)	0	0	0	0
Treasury shares purchased	(937)	0	0	0	(937)	0
Treasury shares purchased (in shares)				0	(29,143)
Shares issued under employee benefit plans and other	431	0	0	1	0	430
Shares issued under employee benefit plans and other (in shares)				17,065	0
Shares and options issued under stock plans and an income tax benefit	12,566	0	0	43	937	11,586
Shares and options issued under stock plans (in shares)				637,981	29,143
Balance - end of year at Dec. 31, 2010	187,467	147,542	(549)	1,917	0	38,557
Balance - end of year (in shares) at Dec. 31, 2010				28,752,325	0
Net earnings	38,765	38,765	0	0	0	0
Other comprehensive income (loss)	(389)	0	(389)	0	0	0
Dividends	(5,237)	(5,237)	0	0	0	0
Treasury shares purchased	(109)	0	0	0	(109)	0
Treasury shares purchased (in shares)				0	(19,545)
Shares issued under employee benefit plans and other	475	0	0	1	51	423
Shares issued under employee benefit plans and other (in shares)				10,962	1,280
Shares and options issued under stock plans and an income tax benefit	11,037	0	0	26	58	10,953
Shares and options issued under stock plans (in shares)				402,434	18,265
Balance - end of year at Dec. 31, 2011	232,009	181,070	(938)	1,944	0	49,933
Balance - end of year (in shares) at Dec. 31, 2011				29,165,721	0
Net earnings	40,005	40,005	0	0	0	0
Other comprehensive income (loss)	179	0	179	0	0	0
Dividends	(6,466)	(6,466)	0	0	0	0
Treasury shares purchased	(1,699)	0	0	0	(1,699)	0
Treasury shares purchased (in shares)				0	(43,680)
Shares issued under employee benefit plans and other	311	0	0	1	0	310
Shares issued under employee benefit plans and other (in shares)				10,145	0
Shares and options issued under stock plans and an income tax benefit	8,673	0	0	19	1,699	6,955
Shares and options issued under stock plans (in shares)				278,305	43,680
Balance - end of year at Dec. 31, 2012	$ 273,012	$ 214,609	$ (759)	$ 1,964	$ 0	$ 57,198
Balance - end of year (in shares) at Dec. 31, 2012				29,454,171	0