Insurance (Guarantees Related to Annuity Contracts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Variable Annuity Guarantees: | Guaranteed Death Benefits
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	$ 56,235	$ 66,724
Separate account value	37,342	45,431
Net amount at risk	$ 2,768	$ 1,238
Average attained age of contractholders	66 years	65 years
Variable Annuity Guarantees: | Guaranteed Annuitization Benefits
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	$ 21,628	$ 26,223
Separate account value	19,839	24,336
Net amount at risk	$ 483	$ 525
Average attained age of contractholders	65 years	65 years
Other Annuity Guarantees: | Guaranteed Annuitization Benefits
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	$ 1,272	$ 1,424
Net amount at risk	$ 489	$ 569
Average attained age of contractholders	50 years	50 years