Insurance (Guarantees Related to Annuity Contracts) (Details) - Variable Annuity Guarantees - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Guaranteed Death Benefits
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value (3)	$ 101,827	$ 103,830
Separate account value	97,237	98,897
Net amount at risk	$ 6,726	$ 8,168
Average attained age of contractholders	67 years	66 years
Guaranteed Annuitization Benefits
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value (3)	$ 57,370	$ 58,615
Separate account value	56,048	57,284
Net amount at risk	$ 2,906	$ 2,088
Average attained age of contractholders	67 years	66 years