CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands	Common Stock Issued [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2008	$ 309	$ 139,415	$ (147,952)	$ 0	$ 216,707	$ 208,479
Balance (shares) at Dec. 31, 2008	30,839
Purchase of treasury stock, at cost	0	0	(2,024)	0	0	(2,024)
Exercise of stock options	0	(1,873)	4,711	0	0	2,838
Income tax expense from stock- based compensation, net	0	(372)	0	0	0	(372)
Stock-based compensation expense	0	1,462	8,602	0	0	10,064
Other	0	(81)	951	0	0	870
Dividends paid	0	0	0	0	(13,272)	(13,272)
Unrealized gain on marketable securities, net of tax	0	0	0	3	0	3
Net income	0	0	0	0	16,574	16,574
Comprehensive income	0	0	0	0	0	16,577
Balance at Dec. 31, 2009	309	138,551	(135,712)	3	220,009	223,160
Balance (shares) at Dec. 31, 2009	30,839
Purchase of treasury stock, at cost	0	0	(7,852)	0	0	(7,852)
Exercise of stock options	0	(1,963)	9,146	0	0	7,183
Income tax expense from stock- based compensation, net	0	25	0	0	0	25
Stock-based compensation expense	0	(966)	9,092	0	0	8,126
Other	0	(40)	862	0	0	822
Dividends paid	0	0	0	0	(13,527)	(13,527)
Unrealized gain on marketable securities, net of tax	0	0	0	18	0	18
Net income	0	0	0	0	22,440	22,440
Comprehensive income	0	0	0	0	0	22,458
Balance at Dec. 31, 2010	309	135,607	(124,464)	21	228,922	240,395
Balance (shares) at Dec. 31, 2010	30,839
Purchase of treasury stock, at cost	0	0	(25,079)	0	0	(25,079)
Exercise of stock options	0	(1,042)	4,998	0	0	3,956
Income tax expense from stock- based compensation, net	0	1,663	0	0	0	1,663
Stock-based compensation expense	0	(416)	9,017	0	0	8,601
Other	0	59	881	0	0	940
Dividends paid	0	0	0	0	(15,742)	(15,742)
Unrealized gain on marketable securities, net of tax	0	0	0	3	0	3
Net income	0	0	0	0	30,470	30,470
Comprehensive income	0	0	0	0	0	30,473
Balance at Dec. 31, 2011	$ 309	$ 135,871	$ (134,647)	$ 24	$ 243,650	$ 245,207
Balance (shares) at Dec. 31, 2011	30,839