Income Taxes	9 Months Ended
Oct. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We compute the year-to-date income tax provision by applying the estimated annual effective tax rate to the year-to-date pre-tax income or loss and adjusting for discrete tax items in the period. We reported an income tax benefit of $5 million and an income tax provision of $6 million for the nine months ended October 31, 2018 and 2017, respectively. The income tax benefit for the nine months ended October 31, 2018 was primarily attributable to the application of intra-period tax allocation rules related to gains from comprehensive income and excess tax benefits in certain foreign jurisdictions from share-based compensation. The income tax benefit was partially offset by state taxes and income tax expenses in profitable foreign jurisdictions. The income tax provision for the nine months ended October 31, 2017 was primarily attributable to state taxes and income tax expenses in profitable foreign jurisdictions. We are subject to income tax audits in the U.S. and foreign jurisdictions. We record liabilities related to uncertain tax positions and believe that we have provided adequate reserves for income tax uncertainties in all open tax years. Due to our history of tax losses, all years remain open to tax audit. We periodically evaluate the realizability of our net deferred tax assets based on all available evidence, both positive and negative. The realization of net deferred tax assets is dependent on our ability to generate sufficient future taxable income during periods prior to the expiration of tax attributes to fully utilize these assets. As of October 31, 2018, we continue to maintain a full valuation allowance on our deferred tax assets except in certain jurisdictions. In December 2017, the SEC staff issued Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act, which allows companies to record provisional amounts for the Tax Act during a measurement period not to extend beyond one year of the enactment date. As of October 31, 2018, we did not have any significant adjustments to our initial assessment performed as of January 31, 2018. We will continue our analysis for all the tax effects of the Tax Act, which are still subject to change during the measurement period, and anticipate further guidance on accounting interpretations from the FASB and application of the Tax Act from the Department of the Treasury.

Income Taxes

We compute the year-to-date income tax provision by applying the estimated annual effective tax rate to the year-to-date pre-tax income or loss and adjusting for discrete tax items in the period. We reported an income tax benefit of $5 million and an income tax provision of $6 million for the nine months ended October 31, 2018 and 2017, respectively. The income tax benefit for the nine months ended October 31, 2018 was primarily attributable to the application of intra-period tax allocation rules related to gains from comprehensive income and excess tax benefits in certain foreign jurisdictions from share-based compensation. The income tax benefit was partially offset by state taxes and income tax expenses in profitable foreign jurisdictions. The income tax provision for the nine months ended October 31, 2017 was primarily attributable to state taxes and income tax expenses in profitable foreign jurisdictions.

We are subject to income tax audits in the U.S. and foreign jurisdictions. We record liabilities related to uncertain tax positions and believe that we have provided adequate reserves for income tax uncertainties in all open tax years. Due to our history of tax losses, all years remain open to tax audit.

We periodically evaluate the realizability of our net deferred tax assets based on all available evidence, both positive and negative. The realization of net deferred tax assets is dependent on our ability to generate sufficient future taxable income during periods prior to the expiration of tax attributes to fully utilize these assets. As of October 31, 2018, we continue to maintain a full valuation allowance on our deferred tax assets except in certain jurisdictions.

In December 2017, the SEC staff issued Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act, which allows companies to record provisional amounts for the Tax Act during a measurement period not to extend beyond one year of the enactment date. As of October 31, 2018, we did not have any significant adjustments to our initial assessment performed as of January 31, 2018. We will continue our analysis for all the tax effects of the Tax Act, which are still subject to change during the measurement period, and anticipate further guidance on accounting interpretations from the FASB and application of the Tax Act from the Department of the Treasury.