CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $)	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]
Balance at Dec. 31, 2011	$ 245,207,000	$ 309,000	$ 135,871,000	$ (134,647,000)	$ 24,000	$ 243,650,000
Balance (shares) at Dec. 31, 2011		30,839,000
Purchase of treasury stock, at cost	(13,773,000)	0	0	(13,773,000)	0	0
Repurchase of common stock	(3,162,000)	(1,000)	(3,161,000)	0	0	0
Repurchase of common stock (in shares)		(81,000)
Exercise of stock options	2,249,000	0	(1,630,000)	3,879,000	0	0
Income tax benefit from stock-based compensation, net	1,751,000	0	1,751,000	0	0	0
Stock-based compensation expense	9,814,000	0	289,000	9,525,000	0	0
Other	1,153,000	0	87,000	1,066,000	0	0
Dividends paid	(42,728,000)	0	0	0	0	(42,728,000)
Unrealized gain (loss) on marketable securities, net of tax	(8,000)	0	0	0	(8,000)	0
Net income	40,402,000	0	0	0	0	40,402,000
Balance at Dec. 31, 2012	240,905,000	308,000	133,207,000	(133,950,000)	16,000	241,324,000
Balance (shares) at Dec. 31, 2012		30,758,000
Purchase of treasury stock, at cost	(17,229,000)	0	0	(17,229,000)	0	0
Repurchase of treasury stock (in shares)	479,903
Exercise of stock options	1,448,000	0	(790,000)	2,238,000	0	0
Income tax benefit from stock-based compensation, net	1,259,000	0	1,259,000	0	0	0
Stock-based compensation expense	11,103,000	0	1,798,000	9,305,000	0	0
Other	1,127,000	0	179,000	948,000	0	0
Dividends paid	(17,386,000)	0	0	0	0	(17,386,000)
Unrealized gain (loss) on marketable securities, net of tax	13,000	0	0	0	13,000	0
Net income	32,032,000	0	0	0	0	32,032,000
Balance at Dec. 31, 2013	253,272,000	308,000	135,653,000	(138,688,000)	29,000	255,970,000
Balance (shares) at Dec. 31, 2013		30,758,000
Purchase of treasury stock, at cost	(20,769,000)	0	0	(20,769,000)	0	0
Repurchase of treasury stock (in shares)	580,804
Exercise of stock options	279,000	0	(180,000)	459,000	0	0
Income tax benefit from stock-based compensation, net	488,000	0	488,000	0	0	0
Stock-based compensation expense	11,053,000	0	1,592,000	9,461,000	0	0
Other	1,288,000	0	216,000	1,072,000	0	0
Dividends paid	(69,493,000)	0	0	0	0	(69,493,000)
Unrealized gain (loss) on marketable securities, net of tax	(26,000)	0	0	0	(26,000)	0
Net income	28,004,000	0	0	0	0	28,004,000
Balance at Dec. 31, 2014	$ 204,096,000	$ 308,000	$ 137,769,000	$ (148,465,000)	$ 3,000	$ 214,481,000
Balance (shares) at Dec. 31, 2014		30,758,000