Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 7,601	$ 8,073
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	4,777	4,500
Provision for doubtful accounts	(263)	208
Provision for warranty and returns	312	0
Stock compensation	1,231	978
Loss (gain) on disposal of property and equipment	27	0
Bond premium amortization	357	19
Cash provided (used) by changes in operating assets and liabilities
Accounts receivable	1,931	5,085
Inventories	3,768	(6,186)
Prepaid expenses and other assets	898	(252)
Accounts payable	(1,610)	2,764
Accrued liabilities	(2,608)	(2,091)
Deferred revenue	0	(278)
Prepaid and deferred income taxes	1,915	2,347
Net cash provided by operating activities	18,336	15,167
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(3,632)	(4,942)
Proceeds from sale of asset	10	0
Intangible asset additions	(287)	0
Purchases of investment securities	(22,424)	(24,530)
Proceeds from sale of investment securities	21,442	3,304
Net cash provided (used) by investing activities	(4,891)	(26,168)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	5,684	1,027
Proceeds from employee stock purchase plan	1,081	909
Tax benefits from exercise of stock options	1,626	280
Purchase of treasury stock	0	0
Net cash provided (used) by financing activities	8,391	2,216
Effect of exchange rate changes on cash	677	1,049
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	22,513	(7,736)
CASH AND CASH EQUIVALENTS, beginning of period	99,590	78,850
CASH AND CASH EQUIVALENTS, end of period	122,103	71,114
NON-CASH INVESTING ACTIVITIES
Accrued liabilities for property and equipment	$ 588	$ 0