Income Taxes	3 Months Ended
Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	14. Income Taxes The effective tax rate was 20.8 percent and 21.5 percent for the three months ended March 31, 2019 and 2018, respectively. The change in tax rate primarily reflects the resolution of certain prior years’ tax items in the current period. We are under continuous examination by the Internal Revenue Service (IRS) and tax authorities in other countries and states in which we have significant business operations. The tax years under examination and open for examination vary by jurisdiction. In 2018 we settled our US federal income tax audits for tax years 2008-2014, and the statute of limitations for these years remain open through 2019. Tax years from 2015 onwards are open for examination by the IRS. We believe it is reasonably possible that our unrecognized tax benefits could decrease within the next 12 months by as much as $113 million, principally as a result of potential resolutions of prior years’ tax items with various taxing authorities. The prior years’ tax items include unrecognized tax benefits relating to the deductibility of certain expenses or losses and the attribution of taxable income to a particular jurisdiction or jurisdictions. Of the $113 million of unrecognized tax benefits, approximately $95 million relates to amounts that, if recognized, would impact the effective tax rate in a future period.

14. Income Taxes

The effective tax rate was 20.8 percent and 21.5 percent for the three months ended March 31, 2019 and 2018, respectively. The change in tax rate primarily reflects the resolution of certain prior years’ tax items in the current period.

We are under continuous examination by the Internal Revenue Service (IRS) and tax authorities in other countries and states in which we have significant business operations. The tax years under examination and open for examination vary by jurisdiction. In 2018 we settled our US federal income tax audits for tax years 2008-2014, and the statute of limitations for these years remain open through 2019. Tax years from 2015 onwards are open for examination by the IRS.

We believe it is reasonably possible that our unrecognized tax benefits could decrease within the next 12 months by as much as $113 million, principally as a result of potential resolutions of prior years’ tax items with various taxing authorities. The prior years’ tax items include unrecognized tax benefits relating to the deductibility of certain expenses or losses and the attribution of taxable income to a particular jurisdiction or jurisdictions. Of the $113 million of unrecognized tax benefits, approximately $95 million relates to amounts that, if recognized, would impact the effective tax rate in a future period.