Income Taxes (Tables)

12 Months Ended

Dec. 31, 2012

Income Taxes [Abstract]

Components of deferred income tax assets and liabilities

	2012			2011
Deferred income tax assets:
Net operating loss carryforward	$	46,531		$	634,802
Deferred warranty revenue		1,759,130			1,674,984
Inventory reserve		905,892			1,712,978
Non-qualified and Non-employee stock option expense		3,682,049			2,842,811
Capitalized research and development		8,191,276			9,677,167
Alternative minimum tax carryforward		1,406,045			1,657,287
Research and development tax credit carryforward		2,936,418			5,088,136
Impairment Loss		230,415			902,675
Deferred Legal Settlement		722,793			1,277,323
Reserves, accruals, and other		1,925,307			1,905,311
Total deferred income tax assets		21,805,856			27,373,474
Deferred income tax liabilities:
Depreciation		(662,172	)		(3,133,145	)
Amortization		(141,885	)		(126,659	)
Total deferred income tax liabilities		(804,057	)		(3,259,804	)
Net deferred income tax assets before valuation allowance		21,001,799			24,113,670
Less: Valuation allowance		—			(1,428,572	)
Net deferred income tax assets	$	21,001,799		$	22,685,098

Net deferred tax assets

	2012		2011
Current deferred tax assets, net	$	9,395,987	$	9,968,929
Long-term deferred tax assets, net		11,605,812		12,716,169
Total	$	21,001,799	$	22,685,098

Significant components of the provision (benefit) for income taxes

	2012			2011			2010
Current:
Federal	$	384,123		$	133,220		$	270,437
State		172,739			59,428			71,494
Total current		556,862			192,648			341,931
Deferred:
Federal		7,778,464			(3,252,769	)		(939,803	)
State		(1,382,203	)		770,687			(148,574	)
Total deferred		6,396,261			(2,482,082	)		(1,088,377	)
Tax provision (benefit) recorded as an increase (decrease)in liability for unrecorded tax benefits		920,497			(299,441	)		17,061
Provision (benefit) for income taxes	$	7,873,620		$	(2,588,875	)	$	(729,385	)

Reconciliation of the Company's effective income tax rate to the federal statutory rate

	2012			2011			2010
Federal income tax at the statutory rate	$	7,913,977		$	(3,370,059	)	$	(1,789,837	)
State income taxes, net of federal benefit		968,902			(357,226	)		(103,651	)
Permanent differences (i)		330,216			680,742			870,757
Research and development		(327,256	)		(229,694	)		(163,883	)
Return to provision adjustment (ii)		(270,134	)		(458,172	)		265,028
Change in liability for unrecognized tax benefits		920,497			(299,441	)		17,061
Change in valuation allowance		(1,428,572	)		1,428,572			—
Other		(234,010	)		16,403			175,140
Provision (benefit) for income taxes	$	7,873,620		$	(2,588,875	)	$	(729,385	)
Effective tax rate		34.8	%		26.9	%		14.3	%

(i) Permanent differences include certain expenses that are not deductible for tax purposes including lobbying fees and stock-based compensation expense related to incentive stock options (“ISOs”).

(ii) The 2010 return to provision adjustment was driven by lower than estimated 2009 R&D credits, which reduced the net tax benefit and therefore, the effective tax rate. The 2011 return to provision adjustment was driven by higher than estimated 2010 R&D tax credits, which increased the net tax benefit and therefore, the effective tax rate. The 2012 return to provision adjustment was driven by higher than estimated 2011 R&D tax credits which increased the net tax benefit and therefore, reduced the effective tax rate.

Roll forward of liability for unrecognized tax benefits

	2012		2011			2010
Balance, beginning of period	$	1,982,399	$	2,281,840		$	2,264,779
Increase in previous year tax positions		659,341		—			—
Increase in current year tax positions		151,041		83,298			58,830
Increase (decrease) related to adjustment of previous estimates of activity		110,115		(382,739	)		(41,769	)
Balance, end of period	$	2,902,896	$	1,982,399		$	2,281,840