Income Taxes	9 Months Ended
Sep. 30, 2013
Income Tax Disclosure [Abstract]
Income Taxes	6. Income taxes *Deferred Tax Assets* The net deferred income tax assets at September 30, 2013, include capitalized research and development costs, research and development tax credits, non-qualified stock-based compensation expense, deferred warranty revenue, warranty and inventory reserves, accrued vacation, and other items, partially offset by accelerated depreciation expense. The Company’s total current and long-term net deferred tax assets at September 30, 2013 are $19.8 million. In preparing the Company’s condensed consolidated financial statements, management assesses the likelihood that its deferred tax assets will be realized from future taxable income. In evaluating the Company’s ability to recover its deferred income tax assets, management considers all available positive and negative evidence, including its operating results, ongoing tax planning and forecasts of future taxable income on a jurisdiction by jurisdiction basis. A valuation allowance is established if it is determined that it is more likely than not that some portion or all of the net deferred tax assets will not be realized. Management exercises significant judgment in determining its provisions for income taxes, its deferred tax assets and liabilities, and its future taxable income for purposes of assessing its ability to utilize any future tax benefit from its deferred tax assets. Although management believes that its tax estimates are reasonable, the ultimate tax determination involves significant judgments that could become subject to audit by tax authorities in the ordinary course of business, as well as the generation of sufficient future taxable income. Management has determined that it is more likely than not that future sales and profitability will allow for the utilization of the deferred tax assets. However, the deferred tax asset could be reduced or a valuation allowance could be recorded in the near-term if estimates of future taxable income during the carry forward period change. The Company has completed research and development tax credit studies which identified approximately $7.8 million in tax credits for federal, Arizona and California income tax purposes related to the 2003 through 2013 tax years, net of the federal benefit on the Arizona and California R&D tax credits. Management has made the determination that it is more likely than not that the full benefit of the R&D tax credit will not be sustained on examination and recorded a liability for unrecognized tax benefits of $2.9 million as of September 30, 2013. In addition, management has accrued approximately $0.2 million for estimated uncertain tax positions related to certain state income tax liabilities. As of September 30, 2013, management does not expect the amount of the unrecognized tax benefit liability to increase or decrease significantly within the next 12 months. Should the unrecognized tax benefit of $3.1 million be recognized, the Company’s effective tax rate would be favorably impacted. *Effective Tax Rate* The Company’s overall effective tax rate for the nine months ended September 30, 2013 was 32.2%, which is below the federal statutory rate due to deductions related to disqualifying dispositions of Incentive Stock Options (“ISOs”) during the year, a credit for domestic production activities deduction, and a favorable 2012 return to provision adjustment taken in the third quarter of 2013. When an employee exercises ISOs and sells the related stock prior to the mandatory holding period, the associated expense becomes a reduction to the Company’s taxable income and represents a permanent benefit in the tax rate. The effect of these items on the federal tax rate was partially offset by the impact of state taxes and non-deductible expenses for items such as ISO book expense, meals and entertainment expense and lobbying fees. The Company’s estimated effective tax rate before discrete adjustments for the full year of 2013 is approximately 38.2%.

6. Income taxes

Deferred Tax Assets

The net deferred income tax assets at September 30, 2013, include capitalized research and development costs, research and development tax credits, non-qualified stock-based compensation expense, deferred warranty revenue, warranty and inventory reserves, accrued vacation, and other items, partially offset by accelerated depreciation expense. The Company’s total current and long-term net deferred tax assets at September 30, 2013 are $19.8 million.

In preparing the Company’s condensed consolidated financial statements, management assesses the likelihood that its deferred tax assets will be realized from future taxable income. In evaluating the Company’s ability to recover its deferred income tax assets, management considers all available positive and negative evidence, including its operating results, ongoing tax planning and forecasts of future taxable income on a jurisdiction by jurisdiction basis. A valuation allowance is established if it is determined that it is more likely than not that some portion or all of the net deferred tax assets will not be realized. Management exercises significant judgment in determining its provisions for income taxes, its deferred tax assets and liabilities, and its future taxable income for purposes of assessing its ability to utilize any future tax benefit from its deferred tax assets. Although management believes that its tax estimates are reasonable, the ultimate tax determination involves significant judgments that could become subject to audit by tax authorities in the ordinary course of business, as well as the generation of sufficient future taxable income. Management has determined that it is more likely than not that future sales and profitability will allow for the utilization of the deferred tax assets. However, the deferred tax asset could be reduced or a valuation allowance could be recorded in the near-term if estimates of future taxable income during the carry forward period change.

The Company has completed research and development tax credit studies which identified approximately $7.8 million in tax credits for federal, Arizona and California income tax purposes related to the 2003 through 2013 tax years, net of the federal benefit on the Arizona and California R&D tax credits. Management has made the determination that it is more likely than not that the full benefit of the R&D tax credit will not be sustained on examination and recorded a liability for unrecognized tax benefits of $2.9 million as of September 30, 2013. In addition, management has accrued approximately $0.2 million for estimated uncertain tax positions related to certain state income tax liabilities. As of September 30, 2013, management does not expect the amount of the unrecognized tax benefit liability to increase or decrease significantly within the next 12 months. Should the unrecognized tax benefit of $3.1 million be recognized, the Company’s effective tax rate would be favorably impacted.

Effective Tax Rate

The Company’s overall effective tax rate for the nine months ended September 30, 2013 was 32.2%, which is below the federal statutory rate due to deductions related to disqualifying dispositions of Incentive Stock Options (“ISOs”) during the year, a credit for domestic production activities deduction, and a favorable 2012 return to provision adjustment taken in the third quarter of 2013. When an employee exercises ISOs and sells the related stock prior to the mandatory holding period, the associated expense becomes a reduction to the Company’s taxable income and represents a permanent benefit in the tax rate. The effect of these items on the federal tax rate was partially offset by the impact of state taxes and non-deductible expenses for items such as ISO book expense, meals and entertainment expense and lobbying fees. The Company’s estimated effective tax rate before discrete adjustments for the full year of 2013 is approximately 38.2%.