Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 16,750	$ 17,566
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	9,533	9,052
Provision for doubtful accounts	(152)	437
Provision for warranty and returns	247
Stock compensation	3,042	1,979
Loss (gain) on disposal of property and equipment	27	(56)
Bond premium amortization	985	399
Cash provided (used) by changes in operating assets and liabilities
Accounts receivable	(850)	3,908
Inventories	3,707	(4,025)
Prepaid expenses and other assets	821	(1,373)
Accounts payable	(608)	1,286
Accrued liabilities	1,582	(599)
Deferred revenue	0	(254)
Prepaid and deferred income taxes	(3,612)	(2,857)
Net cash provided by operating activities	31,472	25,463
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(8,222)	(9,755)
Proceeds from sale of asset	10	0
In	(620)	0
Proceeds from insurance	0	2,781
Purchases of investment securities	(53,966)	(32,236)
Proceeds from sale of investment securities	41,062	12,900
Net cash provided (used) by investing activities	(21,736)	(26,310)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	9,333	4,572
Proceeds from employee stock purchase plan	1,081	909
Tax benefits from exercise of stock options	2,758	2,717
Net cash provided (used) by financing activities	13,172	8,198
Effect of exchange rate changes on cash	(938)	1,167
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	21,970	8,518
CASH AND CASH EQUIVALENTS, beginning of period	99,590	78,850
CASH AND CASH EQUIVALENTS, end of period	121,560	87,368
NON-CASH INVESTING ACTIVITIES
Accrued liabilities for property and equipment	$ 77	$ 262