Income Taxes	6 Months Ended
Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective tax rate for the three months ended June 30, 2018 and 2017 was 12.1% and 1.9%, respectively, and the effective tax rate for the six months ended June 30, 2018 and 2017 was 19.8% and 22.0%, respectively. The effective tax rate for the six months ended June 30, 2018 and 2017 included a $2 million and $4 million charge, respectively, from the write-off of deferred tax assets associated with the expiration of out-of-the-money vested stock options and the vesting of restricted stock. The effective tax rate for the three and six months ended June 30 2018 included a $3 million and $6 million benefit, respectively, from the resolution of certain tax examinations. The effective tax rate for the three and six months ended June 30, 2017 included a $10 million and $14 million benefit, respectively, from the resolution of certain tax examinations. The provisional amounts recorded under Staff Accounting Bulletin No. 118 in 2017 have been adjusted and both the three and six month periods ended June 30, 2018 include a benefit of $9 million related to the re-measurement of deferred tax assets. The amounts recorded as of December 31, 2017 and adjusted June 30, 2018 remain provisional and further adjustments are expected to be made during the measurement period. As is the case with other large corporations, our tax returns are examined by tax authorities in the U.S. and other global taxing jurisdictions in which we have operations. As a result, it is reasonably possible that the amount of unrecognized tax benefits will decrease in the next 12 months, and this decrease could be up to 20% of our unrecognized tax benefits. The IRS examinations of our consolidated U.S. income tax returns for tax years prior to 2013 are closed to audit; however, various post-2006 U.S. state and local tax returns are still subject to examination. In Canada, the examination of our tax filings prior to 2012 are closed to audit, except for the pending application of legal principles to specific issues arising in earlier years. Other significant jurisdictions include France, which is closed to audit through the end of 2014, Germany, which is closed to audit through the end of 2012 and the UK, which, except for an item under appeal, is closed to audit through the end of 2015. We also have other less significant tax filings currently subject to examination.

Income Taxes

The effective tax rate for the three months ended June 30, 2018 and 2017 was 12.1% and 1.9%, respectively, and the effective tax rate for the six months ended June 30, 2018 and 2017 was 19.8% and 22.0%, respectively. The effective tax rate for the six months ended June 30, 2018 and 2017 included a $2 million and $4 million charge, respectively, from the write-off of deferred tax assets associated with the expiration of out-of-the-money vested stock options and the vesting of restricted stock. The effective tax rate for the three and six months ended June 30 2018 included a $3 million and $6 million benefit, respectively, from the resolution of certain tax examinations. The effective tax rate for the three and six months ended June 30, 2017 included a $10 million and $14 million benefit, respectively, from the resolution of certain tax examinations.

The provisional amounts recorded under Staff Accounting Bulletin No. 118 in 2017 have been adjusted and both the three and six month periods ended June 30, 2018 include a benefit of $9 million related to the re-measurement of deferred tax assets. The amounts recorded as of December 31, 2017 and adjusted June 30, 2018 remain provisional and further adjustments are expected to be made during the measurement period.

As is the case with other large corporations, our tax returns are examined by tax authorities in the U.S. and other global taxing jurisdictions in which we have operations. As a result, it is reasonably possible that the amount of unrecognized tax benefits will decrease in the next 12 months, and this decrease could be up to 20% of our unrecognized tax benefits.

The IRS examinations of our consolidated U.S. income tax returns for tax years prior to 2013 are closed to audit; however, various post-2006 U.S. state and local tax returns are still subject to examination. In Canada, the examination of our tax filings prior to 2012 are closed to audit, except for the pending application of legal principles to specific issues arising in earlier years. Other significant jurisdictions include France, which is closed to audit through the end of 2014, Germany, which is closed to audit through the end of 2012 and the UK, which, except for an item under appeal, is closed to audit through the end of 2015. We also have other less significant tax filings currently subject to examination.