Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Operating activities:
Net loss	$ (2,291,792)	$ (1,893,992)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation and amortization	357,875	342,424
Stock-based compensation expense	683,908	1,139,122
Amortization of investments	46,765	245,791
Tax benefit (charge) from exercise of stock options	10,100	(14,629)
Other non-cash items	16,817	(28,343)
Changes in assets and liabilities:
Accounts receivable	342,222	(713,955)
Inventories	(1,661,853)	(2,263,975)
Other current assets	(722,576)	(572,687)
Other assets	0	(41,286)
Accounts payable	(439,358)	843,932
Accrued liabilities	(5,000,372)	(4,209,887)
Accrued income taxes	45,744	18,972
Deferred revenue	(243,235)	774,871
Net cash used in operating activities	(8,855,755)	(6,373,642)
Investing activities:
Purchases of property and equipment	(31,048)	(461,615)
Purchases of short-term investments, marketable securities and other investments	(4,000,000)	(2,045,140)
Proceeds from sale of short-term investments, marketable securities and other investments	9,750,000	2,175,000
Net cash from (used in) investing activities	5,718,952	(331,755)
Financing activities:
Proceeds from the exercise of stock options and warrants	2,250	164,608
Tax benefit (charge) from the exercise of stock options	(10,100)	14,629
Net cash (used in) from financing activities	(7,850)	179,237
Effect of exchange rate changes on cash and cash equivalents	24,447	46,329
Net decrease in cash and cash equivalents	(3,120,206)	(6,479,831)
Cash and cash equivalents, beginning of the period	63,077,178	55,099,319
Cash and cash equivalents, end of the period	59,956,972	48,619,488
Supplemental disclosure of cash flow information:
Cash paid for income taxes	140,000	13,000
Supplemental disclosure of noncash financing and investing activities:
Unrealized (loss) gain on marketable securities, net of taxes	$ (24,827)	$ 21,024