Consolidated Statement of Shareholders' Equity (USD $) In Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2011	$ 552,980	$ 84	$ 135,668	$ 434,581	$ (17,353)
Beginning Balance, Shares at Dec. 31, 2011	42,223	42,223
Issuance of common stock under stock option plans	13,104	2	13,102
Issuance of common stock under stock option plans, Shares	614	612
Stock-based compensation expense	3,314		3,314
Excess tax benefit from stock option exercises	2,838		2,838
Payment of dividends	(4,271)			(4,271)
Net income	14,282			14,282
Net unrealized gain on available-for-sale investments, net of tax of $291	1,220				1,220
Foreign currency translation adjustment, net of tax of $206	5,326				5,326
Ending Balance (unaudited) at Apr. 01, 2012	$ 588,793	$ 86	$ 154,922	$ 444,592	$ (10,807)
Ending Balance, Shares (unaudited) at Apr. 01, 2012	42,835	42,835