Insurance (Guarantees Related to Universal and Variable Life Contracts) (Details) - Secondary Guarantees - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Universal Life
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value (3)	$ 5,816	$ 5,957
Net amount at risk	$ 69,664	$ 71,124
Average attained age of policyholders	67 years	66 years
Variable Life
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value (3)	$ 3,677	$ 3,526
Net amount at risk	$ 20,309	$ 21,325
Average attained age of policyholders	51 years	50 years