Insurance (Guarantees Related to Annuity Contracts) (Details) - Variable Annuity Guarantees - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Guaranteed Death Benefits
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value (3)	$ 97,460	$ 92,794
Separate account value	92,798	88,065
Net amount at risk	$ 7,335	$ 10,945
Average attained age of contract holders	69 years	69 years
Guaranteed Annuitization Benefits
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value (3)	$ 55,859	$ 53,330
Separate account value	54,801	52,225
Net amount at risk	$ 4,729	$ 3,903
Average attained age of contract holders	69 years	68 years