Reinsurance - Narrative (Details) - USD ($) $ in Billions	Jun. 30, 2022	Dec. 31, 2021
Effects of Reinsurance [Line Items]
Reinsurance recoverables	$ 76.6	$ 76.3
Investment Grade
Effects of Reinsurance [Line Items]
Reinsurance recoverables, percent	92.00%	92.00%
Investment Grade | General Insurance
Effects of Reinsurance [Line Items]
Reinsurance recoverables, percent	53.00%	52.00%
Investment Grade | Life and Retirement
Effects of Reinsurance [Line Items]
Reinsurance recoverables, percent	39.00%	40.00%
Non-Investment Grade
Effects of Reinsurance [Line Items]
Reinsurance recoverables, percent	7.00%	7.00%
Non-Investment Grade | Captive Insurers
Effects of Reinsurance [Line Items]
Reinsurance recoverables, percent	72.00%	71.00%
Non-Investment Grade | Life and Retirement
Effects of Reinsurance [Line Items]
Reinsurance recoverables, percent	1.00%	1.00%
Not Rated
Effects of Reinsurance [Line Items]
Reinsurance recoverables, percent	1.00%	1.00%