Income Taxes	6 Months Ended
Jun. 27, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income TaxesThe provision for income taxes is determined using an estimated annual effective tax rate, which is generally less than the U.S. federal statutory rate, primarily due to research and development (“R&D”) tax credits. Our effective tax rate may be subject to fluctuations during the year as new information is obtained, which may affect the assumptions used to estimate the annual effective tax rate, including factors such as expected utilization of R&D tax credits, valuation allowances against deferred tax assets, the recognition or derecognition of tax benefits related to uncertain tax positions, and changes in or the interpretation of tax laws in jurisdictions where we conduct business. Also, excess tax benefits and tax detriments related to our equity compensation recognized in the income statement could result in fluctuations in our effective tax rate period-over-period depending on the volatility of our stock price and how many units vest and options exercised in the period. We recognize deferred tax assets and liabilities, using enacted tax rates, for temporary differences between the financial reporting basis and the tax basis of our assets and liabilities along with net operating loss and tax credit carryovers. We record a valuation allowance against our deferred tax assets to reduce the net carrying value to an amount that we believe is more likely than not to be realized. When we establish or reduce our valuation allowances against our deferred tax assets, the provision for income taxes will increase or decrease, respectively, in the period when that determination is made. We recorded income tax expense of $1.2 million for the three months ended June 27, 2020 compared to $1.4 million for the three months ended June 29, 2019. The decrease in income tax expense for the second quarter of 2020 compared to the second quarter of 2019 was primarily due to lower pre-tax income for the second quarter of 2020 compared to the second quarter of 2019, net of lower discrete tax benefits recognized in the second quarter of 2020, mainly related to net windfalls from stock-based compensation and changes to deferred income taxes. We recorded income tax expense of $2.7 million for the six months ended June 27, 2020 compared to $2.4 million for the six months ended June 29, 2019. The increase in income tax expense for the first six months of 2020 compared to the first six months of 2019 was primarily due to lower discrete tax benefits recognized in the first six months of 2020, mainly related to net windfalls from stock-based compensation and changes to deferred income taxes net of lower pre-tax income for the first six months ended of 2020 compared to the first six months ended of 2019. On March 27, 2020, the U.S. enacted the Coronavirus Aid, Relief, and Economic Security Act ("CARES Act") that provides tax relief to individuals and businesses affected by the coronavirus pandemic. We considered the provisions of the CARES Act and determined they do not have a material impact to our income taxes. Our total amount of unrecognized tax benefits was $5.8 million and $5.7 million as of June 27, 2020 and December 31, 2019, respectively. If recognized, $4.2 million would affect the effective tax rate. As a result of statute of limitations set to expire in the fourth quarter of 2020, we expect decreases to our unrecognized tax benefits of approximately $2.0 million in the next twelve months.

Income Taxes

6 Months Ended

Jun. 27, 2020

Income TaxesThe provision for income taxes is determined using an estimated annual effective tax rate, which is generally less than the U.S. federal statutory rate, primarily due to research and development (“R&D”) tax credits. Our effective tax rate may be subject to fluctuations during the year as new information is obtained, which may affect the assumptions used to estimate the annual effective tax rate, including factors such as expected utilization of R&D tax credits, valuation allowances against deferred tax assets, the recognition or derecognition of tax benefits related to uncertain tax positions, and changes in or the interpretation of tax laws in jurisdictions where we conduct business. Also, excess tax benefits and tax detriments related to our equity compensation recognized in the income statement could result in fluctuations in our effective tax rate period-over-period depending on the volatility of our stock price and how many units vest and options exercised in the period. We recognize deferred tax assets and liabilities, using enacted tax rates, for temporary differences between the financial reporting basis and the tax basis of our assets and liabilities along with net operating loss and tax credit carryovers.

We record a valuation allowance against our deferred tax assets to reduce the net carrying value to an amount that we believe is more likely than not to be realized. When we establish or reduce our valuation allowances against our deferred tax assets, the provision for income taxes will increase or decrease, respectively, in the period when that determination is made.

We recorded income tax expense of $1.2 million for the three months ended June 27, 2020 compared to $1.4 million for the three months ended June 29, 2019. The decrease in income tax expense for the second quarter of 2020 compared to the second quarter of 2019 was primarily due to lower pre-tax income for the second quarter of 2020 compared to the second quarter of 2019, net of lower discrete tax benefits recognized in the second quarter of 2020, mainly related to net windfalls from stock-based compensation and changes to deferred income taxes.

We recorded income tax expense of $2.7 million for the six months ended June 27, 2020 compared to $2.4 million for the six months ended June 29, 2019. The increase in income tax expense for the first six months of 2020 compared to the first six months of 2019 was primarily due to lower discrete tax benefits recognized in the first six months of 2020, mainly related to net windfalls from stock-based compensation and changes to deferred income taxes net of lower pre-tax income for the first six months ended of 2020 compared to the first six months ended of 2019.

On March 27, 2020, the U.S. enacted the Coronavirus Aid, Relief, and Economic Security Act ("CARES Act") that provides tax relief to individuals and businesses affected by the coronavirus pandemic. We considered the provisions of the CARES Act and determined they do not have a material impact to our income taxes.

Our total amount of unrecognized tax benefits was $5.8 million and $5.7 million as of June 27, 2020 and December 31, 2019, respectively. If recognized, $4.2 million would affect the effective tax rate. As a result of statute of limitations set to expire in the fourth quarter of 2020, we expect decreases to our unrecognized tax benefits of approximately $2.0 million in the next twelve months.