Variable Annuity and Insurance Guarantees (Separate Account Balance by Type) (Details 5) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Mutual funds
Distribution of separate account balances by asset type for variable annuity contracts providing guaranteed benefits:
Total mutual funds	$ 66,522	$ 74,676
Equity
Distribution of separate account balances by asset type for variable annuity contracts providing guaranteed benefits:
Total mutual funds	39,764	46,038
Bond
Distribution of separate account balances by asset type for variable annuity contracts providing guaranteed benefits:
Total mutual funds	21,190	23,529
Other
Distribution of separate account balances by asset type for variable annuity contracts providing guaranteed benefits:
Total mutual funds	$ 5,568	$ 5,109