Income Taxes	9 Months Ended
Oct. 29, 2017
Notes to financial statements [Abstract]
Income Taxes	Income Taxes We recognized income tax expense of $58 million and $189 million for the third quarter and first nine months of fiscal year 2018, respectively, and $79 million and $168 million for the third quarter and first nine months of fiscal year 2017, respectively. Income tax expense as a percentage of income before income tax for the third quarter and first nine months of fiscal year 2018 was 6.5% and 8.9%, respectively, and 12.8% and 14.2% for the third quarter and first nine months of fiscal year 2017, respectively. The decrease in our effective tax rate for the third quarter and first nine months of fiscal year 2018 as compared to the same periods in the prior fiscal year primarily reflects the recognition of greater tax benefits related to stock-based compensation and a proportional decrease in the amount of earnings subject to United States tax. Our effective tax rates for the first nine months of fiscal years 2018 and 2017 of 8.9% and 14.2%, respectively, were lower than the U.S. federal statutory rate of 35% due primarily to income earned in jurisdictions where the tax rate is lower than the U.S. federal statutory tax rate, tax benefits related to stock-based compensation, and the benefit of the U.S. federal research tax credit. For the first nine months of fiscal year 2018, there have been no material changes to our tax years that remain subject to examination by major tax jurisdictions. Additionally, there have been no material changes to our unrecognized tax benefits and any related interest or penalties since the fiscal year ended January 29, 2017. While we believe that we have adequately provided for all uncertain tax positions, or tax positions where we believe it is not more-likely-than-not that the position will be sustained upon review, amounts asserted by tax authorities could be greater or less than our accrued position. Accordingly, our provisions on federal, state and foreign tax related matters to be recorded in the future may change as revised estimates are made or the underlying matters are settled or otherwise resolved with the respective tax authorities. As of October 29, 2017, we do not believe that our estimates, as otherwise provided for, on such tax positions will significantly increase or decrease within the next twelve months.

Income Taxes

We recognized income tax expense of $58 million and $189 million for the third quarter and first nine months of fiscal year 2018, respectively, and $79 million and $168 million for the third quarter and first nine months of fiscal year 2017, respectively. Income tax expense as a percentage of income before income tax for the third quarter and first nine months of fiscal year 2018 was 6.5% and 8.9%, respectively, and 12.8% and 14.2% for the third quarter and first nine months of fiscal year 2017, respectively.

The decrease in our effective tax rate for the third quarter and first nine months of fiscal year 2018 as compared to the same periods in the prior fiscal year primarily reflects the recognition of greater tax benefits related to stock-based compensation and a proportional decrease in the amount of earnings subject to United States tax.

Our effective tax rates for the first nine months of fiscal years 2018 and 2017 of 8.9% and 14.2%, respectively, were lower than the U.S. federal statutory rate of 35% due primarily to income earned in jurisdictions where the tax rate is lower than the U.S. federal statutory tax rate, tax benefits related to stock-based compensation, and the benefit of the U.S. federal research tax credit.

For the first nine months of fiscal year 2018, there have been no material changes to our tax years that remain subject to examination by major tax jurisdictions. Additionally, there have been no material changes to our unrecognized tax benefits and any related interest or penalties since the fiscal year ended January 29, 2017.

While we believe that we have adequately provided for all uncertain tax positions, or tax positions where we believe it is not more-likely-than-not that the position will be sustained upon review, amounts asserted by tax authorities could be greater or less than our accrued position. Accordingly, our provisions on federal, state and foreign tax related matters to be recorded in the future may change as revised estimates are made or the underlying matters are settled or otherwise resolved with the respective tax authorities. As of October 29, 2017, we do not believe that our estimates, as otherwise provided for, on such tax positions will significantly increase or decrease within the next twelve months.