Variable Annuity and Insurance Guarantees (Separate Account Balances by Type) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Mutual funds
Variable Annuity and Insurance Guarantees
Total mutual funds	$ 72,963	$ 69,090
Equity [Member]
Variable Annuity and Insurance Guarantees
Total mutual funds	44,365	40,622
Bond [Member]
Variable Annuity and Insurance Guarantees
Total mutual funds	23,481	23,142
Other [Member]
Variable Annuity and Insurance Guarantees
Total mutual funds	$ 5,117	$ 5,326