Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Operating activities
Net loss	$ (3,763,432)	$ (5,892,913)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	713,993	702,491
Stock-based compensation expense	1,389,830	2,133,477
Amortization of investments	97,663	424,899
Tax benefit from exercise of stock options	(15,242)	(22,524)
Other non-cash items	137,266	(62,448)
Changes in assets and liabilities:
Accounts receivable	(641,899)	(1,973,267)
Inventories	(4,087,659)	(5,765,014)
Other current assets	(103,238)	(846,986)
Other assets	(200,000)	(42,007)
Accounts payable	(531,992)	960,346
Accrued liabilities	(2,559,731)	(2,033,611)
Accrued income taxes	47,221	40,709
Deferred revenue	(317,066)	1,414,664
Net cash used in operating activities	(9,834,286)	(10,962,184)
Investing activities
Purchases of property and equipment	(463,446)	(702,941)
Purchases of short-term investments, marketable securities and other investments	(14,495,058)	(6,087,680)
Proceeds from sale of short-term investments, marketable securities and other investments	17,744,880	27,900,000
Net cash from investing activities	2,786,376	21,109,379
Financing activities
Proceeds from the exercise of stock options and warrants	15,300	164,608
Tax benefit from the exercise of stock options	15,242	22,524
Net cash from financing activities	30,542	187,132
Effects of exchange rate changes on cash and cash equivalents	(10,188)	82,308
Net (decrease) increase in cash and cash equivalents	(7,027,556)	10,416,635
Cash and cash equivalents, beginning of the period	63,077,178	55,099,319
Cash and cash equivalents, end of the period	56,049,622	65,515,954
Supplemental disclosure of cash flow information
Cash paid for income taxes	140,000	13,000
Supplemental noncash investing activities
Unrealized (loss) gain on marketable securities, net of taxes	$ (24,079)	$ 25,148