Income Taxes	3 Months Ended
Jan. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We compute, on a quarterly basis, an estimated annual effective tax rate considering ordinary income and related income tax expense. For all periods presented, U.S. and certain foreign results are excluded from ordinary income due to ordinary losses for which no benefit can be recognized. Ordinary income refers to income (loss) before income tax expense excluding significant unusual or infrequently occurring items. The tax effect of a significant unusual or infrequently occurring item is recorded in the interim period in which the item occurs. Items included in income tax expense in the periods in which they occur include the tax effects of cumulative changes in tax laws or rates, foreign exchange gains and losses, adjustments to uncertain tax positions, and adjustments to our valuation allowance due to changes in judgment regarding the ability to realize deferred tax assets in future years. On December 22, 2017, the Tax Act was signed into U.S. law. The Tax Act reduces the statutory corporate income tax rate from 35% to 21%, effective January 1, 2018. This rate reduction requires us to remeasure our deferred taxes as of the date the Tax Act was enacted. Our U.S. deferred tax assets, net of deferred tax liabilities, were remeasured and reduced by $1.0 billion, entirely offset by a valuation allowance reduction. As a result, the remeasurement of our deferred tax assets, net of deferred tax liabilities, including the valuation allowance, did not impact our income tax expense or net loss. The Tax Act imposes a tax on the mandatory deemed repatriation of earnings of the Company’s foreign subsidiaries and results in a one-time transition tax. We have provisionally determined that any additional foreign earnings included in taxable income due to deemed repatriation and related income taxes will be offset with existing deferred tax assets. The deferred tax impact has a valuation allowance offset, resulting in no impact on our income tax expense or net loss. Our estimates related to the deemed repatriation may change significantly as the Company determines the effect of foreign earnings, foreign cash balances and any regulatory guidance. The Tax Act also adds many new provisions, including changes to limits on the deductions for executive compensation and interest expense, a tax on global intangible low‐taxed income (“GILTI”), the base erosion anti‐abuse tax (“BEAT”) and a deduction for foreign derived intangible income (“FDII”). We are still evaluating the impact of these provisions of the Tax Act, which do not apply until our taxable year beginning November 1, 2018. Companies can either account for taxes on GILTI as incurred or recognize deferred taxes when basis differences exist that are expected to affect the amount of the GILTI inclusion upon reversal. The Company is electing to account for taxes on GILTI as incurred. We have not completed our accounting for the income tax effects of the Tax Act. However, we have computed estimates or “provisional” amounts as permitted by the SEC’s Staff Accounting Bulletin No. 118 (“SAB”) issued on December 22, 2017. Under the SAB companies are allowed a measurement period of up to one year from the date of enactment to complete the accounting for the effects of the Tax Act. We will continue to evaluate the Tax Act’s impact, which may change significantly as a result of additional Treasury guidance, federal or state legislative actions, or changes in accounting standards or related interpretations. The Company’s analyses performed to date are sufficient to calculate a reasonable estimate of the impacts of the Tax Act. We have evaluated the need to maintain a valuation allowance for deferred tax assets based on our assessment of whether it is more likely than not that deferred tax benefits will be realized through the generation of future taxable income. Appropriate consideration is given to all available evidence, both positive and negative, in assessing the need for a valuation allowance. We continue to maintain a valuation allowance on the majority of our U.S. deferred tax assets as well as certain foreign deferred tax assets that we believe, on a more-likely-than-not basis, will not be realized based on current forecasted results. For all remaining deferred tax assets, while we believe that it is more likely than not that they will be realized, we believe that it is reasonably possible that additional deferred tax asset valuation allowances could be required in the next twelve months. We recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the consolidated financial statements from such a position are measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon ultimate settlement. As of January 31, 2018, the amount of liability for uncertain tax positions was $31 million. The liability at January 31, 2018 has a recorded offsetting tax benefit associated with various issues that total $10 million. If the unrecognized tax benefits are recognized, all would impact our effective tax rate. However, to the extent we continue to maintain a full valuation allowance against certain deferred tax assets, the effect may be in the form of an increase in the deferred tax asset related to our net operating loss carryforward, which would be offset by a full valuation allowance. We recognize interest and penalties related to uncertain tax positions as part of income tax expense. For the three months ended January 31, 2018 and 2017, total interest and penalties related to our uncertain tax positions resulted in an income tax expense of less than $1 million, for both periods. We have open tax years back to 2001 with various significant taxing jurisdictions including the U.S., Canada, Mexico, and Brazil. In connection with the examination of tax returns, contingencies may arise that generally result from differing interpretations of applicable tax laws and regulations as they relate to the amount, timing, or inclusion of revenues or expenses in taxable income, or the sustainability of tax credits to reduce income taxes payable. We believe we have sufficient accruals for our contingent tax liabilities. Annual tax provisions include amounts considered sufficient to pay assessments that may result from examinations of prior year tax returns, although actual results may differ. While it is probable that the liability for unrecognized tax benefits may increase or decrease during the next twelve months, we do not expect any such change would have a material effect on our financial condition, results of operations, or cash flows.

Income Taxes

We compute, on a quarterly basis, an estimated annual effective tax rate considering ordinary income and related income tax expense. For all periods presented, U.S. and certain foreign results are excluded from ordinary income due to ordinary losses for which no benefit can be recognized. Ordinary income refers to income (loss) before income tax expense excluding significant unusual or infrequently occurring items. The tax effect of a significant unusual or infrequently occurring item is recorded in the interim period in which the item occurs. Items included in income tax expense in the periods in which they occur include the tax effects of cumulative changes in tax laws or rates, foreign exchange gains and losses, adjustments to uncertain tax positions, and adjustments to our valuation allowance due to changes in judgment regarding the ability to realize deferred tax assets in future years.

On December 22, 2017, the Tax Act was signed into U.S. law. The Tax Act reduces the statutory corporate income tax rate from 35% to 21%, effective January 1, 2018. This rate reduction requires us to remeasure our deferred taxes as of the date the Tax Act was enacted. Our U.S. deferred tax assets, net of deferred tax liabilities, were remeasured and reduced by $1.0 billion, entirely offset by a valuation allowance reduction. As a result, the remeasurement of our deferred tax assets, net of deferred tax liabilities, including the valuation allowance, did not impact our income tax expense or net loss.

The Tax Act imposes a tax on the mandatory deemed repatriation of earnings of the Company’s foreign subsidiaries and results in a one-time transition tax. We have provisionally determined that any additional foreign earnings included in taxable income due to deemed repatriation and related income taxes will be offset with existing deferred tax assets. The deferred tax impact has a valuation allowance offset, resulting in no impact on our income tax expense or net loss. Our estimates related to the deemed repatriation may change significantly as the Company determines the effect of foreign earnings, foreign cash balances and any regulatory guidance.

The Tax Act also adds many new provisions, including changes to limits on the deductions for executive compensation and interest expense, a tax on global intangible low‐taxed income (“GILTI”), the base erosion anti‐abuse tax (“BEAT”) and a deduction for foreign derived intangible income (“FDII”). We are still evaluating the impact of these provisions of the Tax Act, which do not apply until our taxable year beginning November 1, 2018. Companies can either account for taxes on GILTI as incurred or recognize deferred taxes when basis differences exist that are expected to affect the amount of the GILTI inclusion upon reversal. The Company is electing to account for taxes on GILTI as incurred.

We have not completed our accounting for the income tax effects of the Tax Act. However, we have computed estimates or “provisional” amounts as permitted by the SEC’s Staff Accounting Bulletin No. 118 (“SAB”) issued on December 22, 2017. Under the SAB companies are allowed a measurement period of up to one year from the date of enactment to complete the accounting for the effects of the Tax Act. We will continue to evaluate the Tax Act’s impact, which may change significantly as a result of additional Treasury guidance, federal or state legislative actions, or changes in accounting standards or related interpretations. The Company’s analyses performed to date are sufficient to calculate a reasonable estimate of the impacts of the Tax Act.

We have evaluated the need to maintain a valuation allowance for deferred tax assets based on our assessment of whether it is more likely than not that deferred tax benefits will be realized through the generation of future taxable income. Appropriate consideration is given to all available evidence, both positive and negative, in assessing the need for a valuation allowance. We continue to maintain a valuation allowance on the majority of our U.S. deferred tax assets as well as certain foreign deferred tax assets that we believe, on a more-likely-than-not basis, will not be realized based on current forecasted results. For all remaining deferred tax assets, while we believe that it is more likely than not that they will be realized, we believe that it is reasonably possible that additional deferred tax asset valuation allowances could be required in the next twelve months.

We recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the consolidated financial statements from such a position are measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon ultimate settlement. As of January 31, 2018, the amount of liability for uncertain tax positions was $31 million. The liability at January 31, 2018 has a recorded offsetting tax benefit associated with various issues that total $10 million. If the unrecognized tax benefits are recognized, all would impact our effective tax rate. However, to the extent we continue to maintain a full valuation allowance against certain deferred tax assets, the effect may be in the form of an increase in the deferred tax asset related to our net operating loss carryforward, which would be offset by a full valuation allowance.

We recognize interest and penalties related to uncertain tax positions as part of income tax expense. For the three months ended January 31, 2018 and 2017, total interest and penalties related to our uncertain tax positions resulted in an income tax expense of less than $1 million, for both periods.

We have open tax years back to 2001 with various significant taxing jurisdictions including the U.S., Canada, Mexico, and Brazil. In connection with the examination of tax returns, contingencies may arise that generally result from differing interpretations of applicable tax laws and regulations as they relate to the amount, timing, or inclusion of revenues or expenses in taxable income, or the sustainability of tax credits to reduce income taxes payable. We believe we have sufficient accruals for our contingent tax liabilities. Annual tax provisions include amounts considered sufficient to pay assessments that may result from examinations of prior year tax returns, although actual results may differ. While it is probable that the liability for unrecognized tax benefits may increase or decrease during the next twelve months, we do not expect any such change would have a material effect on our financial condition, results of operations, or cash flows.