Insurance (Guarantees Related to Annuity Contracts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Variable Annuity Guarantees: | Guaranteed Death Benefits
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	$ 177,895	$ 181,413
Separate account value	150,118	151,901
Net amount at risk	$ 8,679	$ 10,339
Average attained age of contractholders	66 years	66 years
Variable Annuity Guarantees: | Guaranteed Annuitization Benefits
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	$ 89,839	$ 91,240
Separate account value	86,355	87,841
Net amount at risk	$ 3,834	$ 2,762
Average attained age of contractholders	66 years	66 years
Other Annuity Guarantees: | Guaranteed Annuitization Benefits
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	$ 1,393	$ 1,560
Net amount at risk	$ 490	$ 422
Average attained age of contractholders	50 years	51 years