CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY AND COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Comprehensive Income
Balance at Dec. 31, 2008	$ 300,495	$ 357		$ 237,644	$ (2,683)	$ 65,177
Balance (in shares) at Dec. 31, 2008		35,658
Comprehensive income:
Net income	14,595					14,595	14,595
Foreign currency translation adjustment	868				868		868
Total comprehensive income	15,463				868	14,595	15,463
Tax benefit from share-based compensation	784			784
Common stock issued under share-based compensation plans	2,863	5	924	1,934
Common stock issued under share-based compensation plans (in shares)		292	61
Common stock repurchased under share-based compensation plans	(1,782)		(1,782)
Common stock repurchased under share-based compensation plans (in shares)			(117)
Conversion of convertible notes (Note 5)	32			32
Conversion of convertible notes (Note 5) (in shares)		3
Share-based compensation	8,543			8,543
Share-based compensation (in shares)		285
Balance at Dec. 31, 2009	326,398	362	(858)	248,937	(1,815)	79,772
Balance (in shares) at Dec. 31, 2009		36,238	(56)
Comprehensive income:
Net income	13,929					13,929	13,929
Foreign currency translation adjustment	(156)				(156)		(156)
Total comprehensive income	13,773				(156)	13,929	13,773
Tax benefit from share-based compensation	(211)			(211)
Common stock issued under share-based compensation plans	1,460	5	2,933	(1,478)
Common stock issued under share-based compensation plans (in shares)		497	219
Common stock repurchased under share-based compensation plans	(948)		(948)
Common stock repurchased under share-based compensation plans (in shares)			(76)
Share repurchases (Note 7)	(43,212)		(43,212)
Share repurchases (Note 7) (in shares)			(3,382)
Conversion of convertible notes (Note 5)	27,168	24		27,144
Conversion of convertible notes (Note 5) (in shares)		2,328
Dividends declared ($0.205 and $0.07 per share for the year ended December 31, 2011 and 2010, respectively)	(2,632)					(2,632)
Share-based compensation	6,727			6,727
Balance at Dec. 31, 2010	328,523	391	(42,085)	281,119	(1,971)	91,069
Balance (in shares) at Dec. 31, 2010		39,063	(3,295)
Comprehensive income:
Net income	12,080					12,080	12,080
Foreign currency translation adjustment	(16)				(16)		(16)
Total comprehensive income	12,064				(16)	12,080	12,064
Tax benefit from share-based compensation	264			264
Common stock issued under share-based compensation plans	2,857	4	4,736	(1,883)
Common stock issued under share-based compensation plans (in shares)		431	367
Common stock repurchased under share-based compensation plans	(900)		(900)
Common stock repurchased under share-based compensation plans (in shares)			(67)
Share repurchases (Note 7)	(9,958)		(9,958)
Share repurchases (Note 7) (in shares)			(745)
Dividends declared ($0.205 and $0.07 per share for the year ended December 31, 2011 and 2010, respectively)	(7,300)					(7,300)
Share-based compensation	7,369			7,369
Balance at Dec. 31, 2011	$ 332,919	$ 395	$ (48,207)	$ 286,869	$ (1,987)	$ 95,849
Balance (in shares) at Dec. 31, 2011		39,494	(3,740)