Variable Annuity and Insurance Guarantees (Separate Account Balance by Type) (Details 5) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Mutual funds
Distribution of separate account balances by asset type for variable annuity contracts providing guaranteed benefits:
Total mutual funds	$ 69,090	$ 68,747
Equity
Distribution of separate account balances by asset type for variable annuity contracts providing guaranteed benefits:
Total mutual funds	40,622	39,806
Bond
Distribution of separate account balances by asset type for variable annuity contracts providing guaranteed benefits:
Total mutual funds	23,142	23,700
Other
Distribution of separate account balances by asset type for variable annuity contracts providing guaranteed benefits:
Total mutual funds	$ 5,326	$ 5,241