Claim, Claim Adjustment Expense and Future Policy Benefit Reserves, Life and Group Policyholder Reserves (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2021	Dec. 31, 2020
Long Term Care Policyholder Reserves [Abstract]
Liability For Future Policy Benefits Pretax Margin	$ 72
Liability for Future Policy Benefits, Period Expense (Income)		$ 74	$ 216
Lower Claim Severity
Long Term Care Policyholder Reserves [Abstract]
Pretax reductions in claim tax and claim adjustment expense reserves	$ (40)	$ (37)	$ (56)
Lower Discount Rate Assumptions and Mortality Assumption Changes
Long Term Care Policyholder Reserves [Abstract]
Pretax reductions in claim tax and claim adjustment expense reserves				$ 2	$ 46