Claim, Claim Adjustment Expense and Future Policy Benefit Reserves (Life & Group Policyholder Reserves) (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2021
Liability for Claims and Claims Adjustment Expense [Abstract]
Liability for unpaid claims and claims adjustment expense, long term care policies, period increase (decrease)	$ (40)	$ (37)	$ (56)
Liability for unpaid claims and claims adjustment expense structured settlement obligations period increase (decrease)	2	46
Liability for future policy benefits, gross premium valuation, pretax margin	$ 72			$ 72
Premium deficiency and future policy benefit		$ 74	$ 216