Investments, Aggregate Contractual or Notional Amounts and Estimated Fair Values Related to Derivative Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
With hedge designation | Interest rate swaps
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/notional amount		$ 675
Asset, estimated fair value
Liability, estimated fair value		(26)
Without hedge designation | Options – purchased | Options – purchased
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/notional amount		135
Asset, estimated fair value		3
Liability, estimated fair value
Without hedge designation | Interest rate swaps
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/notional amount	100	100
Asset, estimated fair value
Liability, estimated fair value		(3)
Without hedge designation | Embedded derivative on funds withheld liability
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/notional amount	270	190
Asset, estimated fair value
Liability, estimated fair value	$ (12)	$ (19)