Insurance (Guarantees Related to Universal and Variable Life Contracts) (Details) - Secondary Guarantees - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Universal Life
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value (3)	$ 6,028	$ 6,099
Net amount at risk (6)	$ 72,121	$ 73,131
Average attained age of policyholders	66 years	65 years
Variable Life
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value (3)	$ 1,078	$ 954
Net amount at risk (6)	$ 12,519	$ 13,040
Average attained age of policyholders	45 years	45 years