Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash Flows from Operating Activities:
Net income (loss)	$ 10,922,936	$ (1,138,815)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Loss on impairment		1,353,857
Loss on write down / disposal of property and equipment, net	305,138	796,353
Depreciation and amortization	5,113,989	6,112,612
Bond premium amortization	27,977	304,346
Provision for doubtful accounts	(124,519)	22,047
Provision / write-off of excess and obsolete inventory	236,819	746,669
Provision for warranty	265,140	249,652
Stock-based compensation expense	2,197,050	2,533,444
Litigation judgment (recovery) expense	(2,200,000)	3,301,243
Deferred income taxes	2,886,003	(2,479,787)
Provision for unrecognized tax benefits	224,152	357,506
Change in assets and liabilities:
Accounts receivable	(2,646,621)	991,401
Inventory	817,110	1,206,962
Prepaids and other assets	(217,426)	(309,166)
Accounts payable and accrued liabilities	2,942,577	1,009,573
Deferred revenue	2,593,512	(284,916)
Customer deposits	(85,674)	(164,171)
Net cash provided by operating activities	23,258,163	14,637,384
Cash Flows from Investing Activities:
Purchases of investments	(6,235,399)	(11,479,493)
Proceeds from maturity of investments	8,137,561	5,000,000
Proceeds from disposal of capital assets		148,000
Purchases of property and equipment	(887,609)	(1,171,193)
Purchases of intangible assets	(337,863)	(310,501)
Net cash provided by (used in) investing activities	676,690	(7,813,187)
Cash Flows from Financing Activities:
Repurchase of common stock	(19,995,950)	(24,888,817)
Proceeds from stock options exercised	730,473	43,546
Net cash used in financing activities	(19,265,477)	(24,845,271)
Effect of exchange rate change on cash and cash equivalents	(4,398)	(88,309)
Net increase (decrease) in cash and cash equivalents	4,664,978	(18,109,383)
Cash and cash equivalents, beginning of period	21,300,733	42,684,241
Cash and cash equivalents, end of period	25,965,711	24,574,858
Supplemental Disclosure:
Cash paid for income taxes - net	44,100	49,659
Non-Cash Transactions:
Property and equipment purchases in accounts payable	$ 34,168	$ 42,473