Income Taxes	9 Months Ended
Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes During the three months ended September 30, 2017 and 2016, we recognized income tax expense of $372.0 and $518.7, respectively, which represent effective tax rates of 33.2% and 45.6%, respectively. The decrease in income tax expense and the effective tax rate was primarily due to the suspension of the non-tax deductible Health Insurance Provider Fee, or HIP Fee, for 2017. For the three months ended September 30, 2016, we recognized additional income tax expense of $100.5 related to the HIP Fee. During the nine months ended September 30, 2017 and 2016, we recognized income tax expense of $1,227.5 and $1,795.4, respectively, which represent effective tax rates of 32.0% and 46.1%, respectively. The decrease in income tax expense was primarily due to the suspension of the non-tax deductible HIP Fee for 2017 and the favorable impact of our recognition of tax benefits during the second quarter of 2017 for prior acquisition costs incurred related to the terminated Merger Agreement with Cigna. For the nine months ended September 30, 2016, we recognized additional income tax expense of $308.8 related to the HIP Fee. The decrease in income tax expense was further due to the recognition of excess tax benefits during the nine months ended September 30, 2017 from the adoption of ASU 2016-09, as discussed in Note 2, "Basis of Presentation and Significant Accounting Policies - Recently Adopted Accounting Guidance." Additionally, during the nine months ended September 30, 2016, we recognized additional California deferred state tax expense resulting from specific California legislation related to Managed Care Organizations that did not recur in 2017. The decrease in the effective tax rate was primarily due to the suspension of the HIP Fee, the deduction of the prior acquisition costs incurred related to the terminated Merger Agreement with Cigna, the excess tax benefits from the adoption of ASU 2016-09 and the additional California deferred state tax expense, discussed above.

Income Taxes

During the three months ended September 30, 2017 and 2016, we recognized income tax expense of $372.0 and $518.7, respectively, which represent effective tax rates of 33.2% and 45.6%, respectively. The decrease in income tax expense and the effective tax rate was primarily due to the suspension of the non-tax deductible Health Insurance Provider Fee, or HIP Fee, for 2017. For the three months ended September 30, 2016, we recognized additional income tax expense of $100.5 related to the HIP Fee.

During the nine months ended September 30, 2017 and 2016, we recognized income tax expense of $1,227.5 and $1,795.4, respectively, which represent effective tax rates of 32.0% and 46.1%, respectively. The decrease in income tax expense was primarily due to the suspension of the non-tax deductible HIP Fee for 2017 and the favorable impact of our recognition of tax benefits during the second quarter of 2017 for prior acquisition costs incurred related to the terminated Merger Agreement with Cigna. For the nine months ended September 30, 2016, we recognized additional income tax expense of $308.8 related to the HIP Fee. The decrease in income tax expense was further due to the recognition of excess tax benefits during the nine months ended September 30, 2017 from the adoption of ASU 2016-09, as discussed in Note 2, "Basis of Presentation and Significant Accounting Policies - Recently Adopted Accounting Guidance." Additionally, during the nine months ended September 30, 2016, we recognized additional California deferred state tax expense resulting from specific California legislation related to Managed Care Organizations that did not recur in 2017. The decrease in the effective tax rate was primarily due to the suspension of the HIP Fee, the deduction of the prior acquisition costs incurred related to the terminated Merger Agreement with Cigna, the excess tax benefits from the adoption of ASU 2016-09 and the additional California deferred state tax expense, discussed above.