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, 2021	Dec. 31, 2020
Secondary Guarantees
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value (1), (3)	$ 13,532	$ 13,426
Net amount at risk (7)	$ 78,416	$ 82,940
Average attained age of policyholders	55 years	54 years
Paid-Up Guarantees
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value (1), (3)	$ 2,718	$ 2,808
Net amount at risk (7)	$ 12,878	$ 13,557
Average attained age of policyholders	66 years	65 years