Derivative Instruments (Cumulative Basis Adjustments For Fair Value Hedges) (Details) $ in Millions	Mar. 31, 2019 USD ($)
Fixed Maturity AFS Securities [Member]
Derivatives, Fair Value [Line Items]
Amortized cost of hedged assets	$ 457
Cumulative amount of fair value hedging adjustment included in the amortized cost of the hedged assets	161
Long-term Debt [Member]
Derivatives, Fair Value [Line Items]
Amortized cost of hedged liabilities	(976)
Cumulative amount of fair value hedging adjustment included in the amortized cost of the hedged liabilities	(101)	[1]
Discontinued Hedges [Member]
Derivatives, Fair Value [Line Items]
Cumulative amount of fair value hedging adjustment included in the amortized cost of the hedged assets	$ (122)

[1] The balance includes $(122) million of unamortized adjustments from discontinued hedges as of March 31, 2019.