Investments Investments (Allowance for credit losses rollforward) (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
		Sep. 30, 2020	Sep. 30, 2020
Rollforward of available-for-Sale securities allowance for credit losses
Beginning balance		$ 13	$ 0	[1]
Additions for which credit losses were not previously recognized		0	13
Ending balance	[2]	$ 13	$ 13

[1] Prior to January 1, 2020, credit losses on Available-for-Sale securities were not recorded in an allowance but were recorded as a reduction of the book value of the security if the security was other-than-temporarily impaired. There is no adoption impact due to the prospective transition for Available-for-Sale securities.

[2] Prior to January 1, 2020, the allowance for credit losses is not applicable to Available-for-Sale securities and Reinsurance recoverables. See Notes 2, 3, 6 and 7 for more information.