Consolidated Statement Of Stockholders' Equity (USD $) In Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Total
Balance at Dec. 31, 2010	$ 396	$ 435,840	$ (230,272)	$ 248,433	$ 4,028	$ 458,425
Issuance of 36 shares of common stock pursuant to the exercise of employee stock options		609				609
Issuance of 8 shares of common stock pursuant to the employee stock purchase plan		153				153
Purchase of 44 treasury shares			(824)			(824)
Stock-based compensation		4,130				4,130
Other	2	(2)
Net income				19,141		19,141
Reclassification adjustment related to marketable securities sold in net unrealized gain position, net of $3 tax provision					(5)	(5)
Change in fair value on available-for-sale securities, net of deferred income tax of $133					228	228
Cumulative translation adjustment					4,735	4,735
Comprehensive income						24,099
Balance at Jun. 30, 2011	$ 398	$ 440,730	$ (231,096)	$ 267,574	$ 8,986	$ 486,592