New Accounting Standards	9 Months Ended
New Accounting Standards	Sep. 30, 2019
Accounting Policies [Abstract]
New Accounting Standards	New Accounting Standards Issued In August 2018, the Financial Accounting Standards Board (FASB) issued an Accounting Standards Update (ASU), which provides additional guidance on the requirements for capitalizing and amortizing implementation costs incurred in a cloud computing arrangement that does not include a software license. This ASU will be effective for fiscal years (including interim periods within those fiscal years) beginning after December 15, 2019 (2020 for calendar-year companies). We do not expect this standard to have a material impact on our financial condition, cash flows, or results of operations. In August 2018, the FASB issued an ASU, which amends the disclosure requirements for fair value measurements. The ASU requires companies to disclose the changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. The ASU also removes current disclosure requirements for the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, the policy for timing of transfers between levels, and the valuation processes for Level 3 fair value measurements. The ASU is effective for fiscal years beginning after December 15, 2019 (2020 for calendar-year companies), and should be applied prospectively for the additions to the disclosure requirements and applied retrospectively to all periods presented for all other amendments. As permitted by the ASU, we elected to partially early adopt the removal of current disclosure requirements and will adopt the new disclosure requirements as of the effective date. We do not expect this standard to have an impact on our financial condition, cash flows, or results of operations. In January 2017, the FASB issued an ASU, which eliminates the requirement to determine the implied fair value of goodwill in measuring an impairment loss. Upon adoption, the measurement of a goodwill impairment will represent the excess of the reporting unit’s carrying value over fair value, limited to the carrying value of goodwill. This ASU is effective for goodwill impairment tests in fiscal years beginning after December 15, 2019 (2020 for calendar-year companies), with early adoption permitted. We do not expect this standard to have a material impact on our financial position or results of operations. In June 2016, the FASB issued an ASU intended to improve the timing, and enhance the accounting and disclosure, of credit losses on financial assets. This update will modify the existing accounting guidance related to the impairment evaluation for available-for-sale debt securities and will result in the creation of an allowance for credit losses as a contra asset account. The ASU will require cumulative-effect changes to retained earnings in the period of adoption, if any occur, and will also require prospective changes on previously recorded impairments. This ASU is effective for fiscal years (including interim periods within those fiscal years) beginning after December 15, 2019 (2020 for calendar-year companies), with early adoption permissible (including interim periods within that fiscal year) beginning after December 15, 2018 (2019 for calendar-year companies). While the ASU creates additional accounting complexities related to the recognition of the impairment losses, and subsequent recoveries, through an allowance for credit losses account, we currently do not expect the ASU to have a material impact on our current method of evaluating securities, premiums receivables, or reinsurance recoverables for credit losses or the timing or recognition of the amounts of impairment losses. Adopted On January 1, 2019, we adopted the ASU that requires lessees to report their operating leases as both an asset and liability on the statement of financial position and to disclose key information about leasing arrangements in the financial statement footnotes. We are reporting our operating leased assets and liabilities as a component of “other assets” and “accounts payable, accrued expenses, and other liabilities,” respectively. We did not restate prior year information. Upon adoption of the ASU, based on our lease portfolio on January 1, 2019, and after applying the practical expedient under which we were not required to reassess any of our existing contracts, classification of our leases, or the initial direct costs for existing leases, we recorded a transition adjustment of $213.0 million for leased assets and $217.6 million for liabilities. The adoption of this ASU had no impact on our results of operations or cash flows. See Note 14 – Leases for further information. On January 1, 2019, we adopted the ASU related to premium amortization on purchased callable debt securities. Under the ASU, the premium is required to be amortized to the earliest call date, which more closely aligns interest income recorded on bonds held at a premium with the economics of the underlying instrument. We applied the ASU on a modified retrospective basis, as required under the standard. Since we have historically used a yield-to-worst scenario for our securities that were purchased at a premium, and the first call on a premium security most often produces the lowest and most conservative yield, the adoption of this standard did not have an impact on our financial condition, cash flows, or results of operations.