Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net income (loss)	$ 14,737,742	$ (7,039,866)	$ (4,384,435)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	6,519,250	8,096,543	7,286,915
Loss on impairment		1,353,857
Loss on write down / disposal of property and equipment, net	160,506	2,800,396	73,061
Loss on disposal of intangibles	194,912	54,356	47,947
Bond premium amortization	28,718	371,304
(Recovery) Provision for doubtful accounts	(242,230)	296,016	48,903
Provision for excess and obsolete inventory	553,701	3,746,149	1,278,284
Provision for warranty	526,563	309,779	843,268
Stock-based compensation expense	3,421,506	3,038,300	3,682,675
Litigation judgment	(2,200,000)	3,301,243
Deferred income taxes	6,396,261	(2,480,856)	(1,088,377)
Provision for unrecognized tax benefits	920,497	(299,441)	17,061
Excess tax benefit from stock-based compensation	(4,712,962)	(9,828)	(52,147)
Change in assets and liabilities:
Accounts and notes receivable	(6,078,875)	1,463,031	1,768,134
Inventory	(62,149)	1,327,801	(4,007,939)
Prepaid expenses and other assets	(625,911)	(373,709)	(1,715,403)
Accounts payable and accrued liabilities	2,724,450	109,051	(3,246,517)
Deferred revenue	4,168,530	296,422	163,876
Customer deposits	86,704	41,169	16,219
Net cash provided by operating activities	26,517,213	17,265,765	731,525
Cash flows from investing activities:
Purchases of investments	(6,242,031)	(11,479,493)
Proceeds from call / maturity of investments	9,640,544	6,000,000
Purchases of property and equipment	(1,333,986)	(1,854,083)	(4,023,691)
Proceeds from disposal of fixed assets	45,511	149,400	30,972
Purchases of intangible assets	(428,983)	(413,466)	(478,983)
Net cash provided by (used in) investing activities	1,681,055	(7,597,642)	(4,471,702)
Cash flows from financing activities:
Repurchase of common stock	(19,995,950)	(32,498,856)
Repurchase of stock options			(124,230)
Proceeds from options exercised	1,929,308	1,427,418	1,001,476
Payments on capital lease obligation	(9,736)
Excess tax benefit from stock-based compensation	4,712,962	9,828	52,147
Net cash (used in) provided by financing activities	(13,363,416)	(31,061,610)	929,393
Effect of exchange rate changes on cash and cash equivalents	(8,794)	9,979	(10,024)
Net increase (decrease) in cash and cash equivalents	14,826,058	(21,383,508)	(2,820,808)
Cash and cash equivalents, beginning of year	21,300,733	42,684,241	45,505,049
Cash and cash equivalents, end of year	$ 36,126,791	$ 21,300,733	$ 42,684,241