Insurance (Guarantees Related to Universal and Variable Life Contracts) (Details) - Universal and Variable Life Contracts - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Secondary Guarantees
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value (1), (2)	$ 5,135	$ 4,909
Net amount at risk (6)	$ 39,919	$ 41,385
Average attained age of policyholders	58 years	57 years
Paid-Up Guarantees
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value (1), (2)	$ 870	$ 899
Net amount at risk (6)	$ 5,612	$ 5,884
Average attained age of policyholders	64 years	64 years