Business, Basis of Presentation and Significant Accounting Policies - Adoption of New Pronouncements (Details) - Accounting Standards Update 2016-13 $ in Millions	Jan. 01, 2020 USD ($)
Unappropriated
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment for adoption of ASU	$ (33)
Mortgage loans on real estate
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment for adoption of ASU	19
Reinsurance Recoverables
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment for adoption of ASU	28
deferred policy acquisition cost
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment for adoption of ASU	5
Deferred Income Tax Charge
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment for adoption of ASU	$ 9