CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net income	$ 68,098	$ 69,869	$ 61,381
Adjustments to reconcile net income to net cash provided by operations:
Stock-based compensation expense	8,520	8,068	3,027
Depreciation of property, plant, and equipment	6,721	5,529	4,685
Amortization of intangible assets	4,137	4,227	5,124
Amortization of discounts or premiums on investments	5,735	6,383	3,195
Realized (gain) loss on sale of investments	(1,625)	181	(10)
Change in deferred income taxes	429	(425)	1,034
Tax effect of stock option exercises	(3,594)	(4,045)	(1,941)
Changes in operating assets and liabilities:
Accounts receivable	5,035	(2,031)	(14,535)
Inventories	1,872	(5,743)	(6,190)
Accrued expenses	(1,974)	2,747	10,134
Accrued income taxes	3,363	(2,865)	9,567
Deferred revenue and customer deposits	(761)	3,316	(4,740)
Return of Japan tax deposit (Note 15)			9,336
Other	5,175	1,064	(3,734)
Net cash provided by operating activities	101,131	86,275	76,333
Cash flows from investing activities:
Purchases of investments	(460,486)	(323,946)	(253,867)
Maturities and sales of investments	431,510	241,557	82,928
Purchases of property, plant, and equipment	(9,878)	(7,820)	(5,852)
Cash received related to discontinued business			315
Net cash used in investing activities	(38,854)	(90,209)	(176,476)
Cash flows from financing activities:
Issuance of common stock under stock option plans	17,468	30,863	28,384
Payment of dividends	(66,213)	(15,114)	(10,014)
Repurchase of common stock		(10,000)
Stock option buyback			(83)
Tax effect of stock option exercises	3,594	4,045	1,941
Net cash provided by (used in) financing activities	(45,151)	9,794	20,228
Effect of foreign exchange rate changes on cash and cash equivalents	(10,069)	(960)	(6,713)
Net change in cash and cash equivalents	7,057	4,900	(86,628)
Cash and cash equivalents at beginning of year	38,103	33,203	119,831
Cash and cash equivalents at end of year	$ 45,160	$ 38,103	$ 33,203