Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes Bipartisan Budget Act of 2018 On February 9, 2018, the Bipartisan Budget Act (“BBA”) of 2018 was signed into law. The BBA includes a retroactive one year tax extenders package back to January 1, 2017, which reinstated several energy investment tax credits that had expired on December 31, 2016. Due to these retroactive provisions, Key recognized additional net investment tax credits in the first quarter of 2018 of $14 million, or a 2.8% reduction to our income tax provision, for energy tax credit transactions entered into during 2017. TCJ Act On December 22, 2017, the TCJ Act was signed into law. This comprehensive tax legislation provides for significant changes to the U.S. Internal Revenue Code of 1986, as amended, that impact corporate taxation requirements, such as the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018. The TCJ Act retains the low-income housing and research and development credits and repeals the corporate alternative minimum tax. Other relevant corporate changes include earlier recognition of certain revenue; accelerating expensing of investments in tangible property, including leasing assets; and limiting several deductions such as FDIC premiums, certain executive compensation, and meals and entertainment expenses. Key was required to re-value certain tax-related assets under the provisions of the TCJ Act at December 31, 2017. Under current U.S. GAAP, deferred tax assets and liabilities are to be adjusted for the effect of a change in tax laws or rates with the effect included in income from continuing operations in the reporting period that includes the enactment date. The tax-related assets consist primarily of deferred tax assets and liabilities and investments in low-income housing transactions. Due to the close proximity of our year end to the date the TCJ Act was signed into law, we estimated the impact of the income tax effects as of December 31, 2017, based upon currently available information which resulted in a reduction to our net income of $161 million. The significant components of this reduction included a $14 million reduction in our investments in certain low-income housing that is reflected in other expenses and a $147 million, or 7.6%, increase in our income tax provision for the twelve months ended December 31, 2017, due to the reduction to our net deferred tax asset and related actions. This reduction was primarily the result of the lower federal corporate income tax rate and was based on information available at that time. During the current quarter, Key completed and filed its 2017 federal income tax return and management finalized its assessment of the initial impact of the TCJ Act and related regulatory guidance. As a result, our income tax provision was increased by $7 million during the quarter, and the total impact to Key of the TCJ Act was a reduction to our net income of $168 million. The accounting for the changes in tax law resulted in stranded tax effects within accumulated other comprehensive income for items that were originally recognized in other comprehensive income rather than in net income. The FASB issued an accounting standard update allowing companies to reclassify stranded tax effects resulting from the TCJ Act from accumulated other comprehensive income to retained earnings. We early adopted this guidance during the quarter ended December 31, 2017, and utilizing the portfolio method reclassified $141 million from accumulated other comprehensive income to retained earnings to eliminate the stranded tax effects. Income Tax Provision In accordance with the applicable accounting guidance, the principal method established for computing the provision for income taxes in interim periods requires us to make our best estimate of the effective tax rate expected to be applicable for the full year. This estimated effective tax rate is then applied to interim consolidated pre-tax operating income to determine the interim provision for income taxes. The effective tax rate, which is the provision for income taxes as a percentage of income from continuing operations before income taxes, was 15.5% for the third quarter of 2018 and 26.9% for the third quarter of 2017. The effective tax rates are below our combined federal and state statutory tax rate of 23.7% for the third quarter of 2018 and 37.2% for the third quarter of 2017, primarily due to income from investments in tax-advantaged assets such as corporate-owned life insurance and credits associated with renewable energy and low-income housing investments. The effective tax rates for the three months ended September 30, 2018, and September 30, 2017, were affected by net discrete income tax benefit of 2.2%, respectively. Deferred Tax Asset At September 30, 2018, from continuing operations we had a net deferred tax asset of $331 million, compared to a net deferred tax asset of $320 million at December 31, 2017, included in “accrued income and other assets” on the balance sheet. To determine the amount of deferred tax assets that are more likely than not to be realized, and therefore recorded, we conduct a quarterly assessment of all available evidence. This evidence includes, but is not limited to, taxable income in prior periods, projected future taxable income, and projected future reversals of deferred tax items. These assessments involve a degree of subjectivity and may undergo change. Based on these criteria, we had a valuation allowance of $11 million at September 30, 2018, and $15 million at December 31, 2017. The valuation allowance is associated with certain state net operating loss carryforwards, state credit carryforwards, and federal and state capital loss carryforwards. Unrecognized Tax Benefits As permitted under the applicable accounting guidance for income taxes, it is our policy to recognize interest and penalties related to unrecognized tax benefits in “income tax expense.” At September 30, 2018, Key’s unrecognized tax benefits were $46 million. Pre-1988 Bank Reserves Acquired in a Business Combination Retained earnings of KeyBank included approximately $92 million of allocated bad debt deductions for which no income taxes have been recorded. Under current federal law, these reserves are subject to recapture into taxable income if KeyBank, or any successor, fails to maintain its bank status under the Internal Revenue Code or makes non-dividend distributions or distributions greater than its accumulated earnings and profits. No deferred tax liability has been established as these events are not expected to occur in the foreseeable future.