CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands	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, 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
Purchase of treasury stock, at cost	(17,229,000)	$ 0	0	(17,229,000)	0	0
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
Purchase of treasury stock, at cost	(20,769,000)	$ 0	0	(20,769,000)	0	0
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
Purchase of treasury stock, at cost	(67,113,000)	$ 0	0	(67,113,000)	0	0
Exercise of stock options	374,000	0	(3,000)	377,000	0	0
Income tax benefit from stock-based compensation, net	2,216,000	0	2,216,000	0	0	0
Stock-based compensation expense	13,345,000	0	4,239,000	9,053,000	0	53,000
Other	1,303,000	0	480,000	823,000	0	0
Dividends paid	(21,153,000)	0	0	0	0	(21,153,000)
Unrealized gain (loss) on marketable securities, net of tax	(3,000)	0	0	0	(3,000)	0
Net income	39,390,000	0	0	0	0	39,390,000
Balance at Dec. 31, 2015	$ 172,455,000	$ 308,000	$ 144,701,000	$ (205,325,000)	$ 0	$ 232,771,000
Balance (shares) at Dec. 31, 2015		30,758