Adoption of ASU 2018-12 - Summary of Changes in Net Asset Position of Ceded MRBs (Details) $ in Millions	Dec. 31, 2020 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Ceded MRBs, Net	$ 336
Accounting Standards Update 2018-12 | Cumulative Effect to Retained Earnings | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Ceded MRBs, Net	121
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Ceded MRBs, Net	215
Variable Annuities
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Ceded MRBs, Net	336
Variable Annuities | Accounting Standards Update 2018-12 | Cumulative Effect to Retained Earnings | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Ceded MRBs, Net	121
Variable Annuities | As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Ceded MRBs, Net	$ 215