Condensed Consolidated Statement of Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance at Dec. 31, 2011	$ 564	$ 47,701	$ 81,101	$ 25	$ 129,391
Balance (in shares) at Dec. 31, 2011	56,397				56,397
Comprehensive income:
Net income	0	0	22,417	0	22,417
Unrealized loss on available-for-sale marketable debt securities	0	0	0	(12)	(12)
Comprehensive income					22,405
Exercise of common stock options	2	1,653	0	0	1,655
Exercise of common stock options (in shares)	208
Tax effect from stock-based compensation	0	2,244	0	0	2,244
Stock-based compensation	1	6,963	0	0	6,964
Stock-based compensation (in shares)	140
Repurchases of common stock	0	(1,214)	0	0	(1,214)
Repurchases of common stock (in shares)	(40)
Balance at Mar. 31, 2012	$ 567	$ 57,347	$ 103,518	$ 13	$ 161,445
Balance (in shares) at Mar. 31, 2012	56,705				56,705