Income Taxes	9 Months Ended
Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes During the three months ended September 30, 2018 and 2017, we recognized income tax expense of $282 and $372, respectively, which represent effective tax rates of 22.7% and 33.2%, respectively. The decrease in income tax expense and effective tax rate was primarily due to the effect of the Tax Cuts and Jobs Act, which reduced the U.S. federal corporate income tax rate from 35% to 21% effective January 1, 2018 and required remeasurement of deferred tax assets and liabilities due to the revisions of 2017 provision estimates at the new rate. The decrease in income tax expense and effective tax rate was partially offset by the reinstatement of the non-tax deductible Health Insurance Provider Fee, or HIP Fee, for 2018, which resulted in additional income tax expense of $76 during the three months ended September 30, 2018. During the nine months ended September 30, 2018 and 2017, we recognized income tax expense of $1,200 and $1,228, respectively, which represent effective tax rates of 26.5% and 32.0%, respectively. The decrease in income tax expense and effective tax rate was primarily due to the effect of the Tax Cuts and Jobs Act. The decrease in income tax expense and effective tax rate was partially offset by the reinstatement of the HIP Fee for 2018, which resulted in additional income tax expense of $243 during the nine months ended September 30, 2018. The decrease in income tax expense and effective tax rate was also partially offset by the tax benefits we recognized during the nine months ended September 30, 2017 for prior acquisition costs incurred related to the terminated merger agreement with Cigna Corporation. At September 30, 2018, we have not completed our accounting for all of the tax effects of the Tax Cuts and Jobs Act. We have made a reasonable estimate of the effects and will continue to make and refine our calculations as additional analysis is completed. Our estimates may also be affected if additional interpretative guidance is issued regarding the Tax Cuts and Jobs Act.

Income Taxes

During the three months ended September 30, 2018 and 2017, we recognized income tax expense of $282 and $372, respectively, which represent effective tax rates of 22.7% and 33.2%, respectively. The decrease in income tax expense and effective tax rate was primarily due to the effect of the Tax Cuts and Jobs Act, which reduced the U.S. federal corporate income tax rate from 35% to 21% effective January 1, 2018 and required remeasurement of deferred tax assets and liabilities due to the revisions of 2017 provision estimates at the new rate. The decrease in income tax expense and effective tax rate was partially offset by the reinstatement of the non-tax deductible Health Insurance Provider Fee, or HIP Fee, for 2018, which resulted in additional income tax expense of $76 during the three months ended September 30, 2018.

During the nine months ended September 30, 2018 and 2017, we recognized income tax expense of $1,200 and $1,228, respectively, which represent effective tax rates of 26.5% and 32.0%, respectively. The decrease in income tax expense and effective tax rate was primarily due to the effect of the Tax Cuts and Jobs Act. The decrease in income tax expense and effective tax rate was partially offset by the reinstatement of the HIP Fee for 2018, which resulted in additional income tax expense of $243 during the nine months ended September 30, 2018. The decrease in income tax expense and effective tax rate was also partially offset by the tax benefits we recognized during the nine months ended September 30, 2017 for prior acquisition costs incurred related to the terminated merger agreement with Cigna Corporation.

At September 30, 2018, we have not completed our accounting for all of the tax effects of the Tax Cuts and Jobs Act. We have made a reasonable estimate of the effects and will continue to make and refine our calculations as additional analysis is completed. Our estimates may also be affected if additional interpretative guidance is issued regarding the Tax Cuts and Jobs Act.