Derivatives (Fair Value Hedges) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Components Excluded from Assessment of Foreign Currency Fair Value Hedge Effectiveness	$ (7)	$ (6)	$ (27)	$ (30)
Net Derivative Gains (Losses) Recognized for Derivatives	(163)	(12)	(328)	52
Net Derivative Gains (Losses) Recognized for Hedged Items	156	11	328	40
Ineffectiveness Recognized in Net Derivative Gains (Losses)	(7)	(1)	0	92
Interest rate swaps \| Fixed Maturity Securities
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	1	1	4	2
Net Derivative Gains (Losses) Recognized for Hedged Items	(2)	0	(4)	(2)
Ineffectiveness Recognized in Net Derivative Gains (Losses)	(1)	1	0	0
Interest rate swaps \| Policyholder account balances
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(108)	(14)	(389)	(16)
Net Derivative Gains (Losses) Recognized for Hedged Items	110	13	392	84
Ineffectiveness Recognized in Net Derivative Gains (Losses)	2	(1)	3	68
Foreign currency swaps \| Foreign-denominated fixed maturity securities AFS and mortgage loans
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	4	(10)	29	(15)
Net Derivative Gains (Losses) Recognized for Hedged Items	(7)	10	(33)	16
Ineffectiveness Recognized in Net Derivative Gains (Losses)	(3)	0	(4)	1
Foreign currency swaps \| Foreign-denominated policyholder account balances [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	15	23	61
Net Derivative Gains (Losses) Recognized for Hedged Items	0	(16)	(23)	(40)
Ineffectiveness Recognized in Net Derivative Gains (Losses)	0	(1)	0	21
Foreign currency forwards \| Foreign-denominated fixed maturity securities AFS and mortgage loans
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(60)	(4)	5	20
Net Derivative Gains (Losses) Recognized for Hedged Items	55	4	(4)	(18)
Ineffectiveness Recognized in Net Derivative Gains (Losses)	$ (5)	$ 0	$ 1	$ 2

Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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The net gain (loss) recognized in earnings in the period relating to components of the gain (loss) on foreign currency fair value hedging instruments excluded from the assessment of fair value hedge effectiveness.

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Amount of gain (loss)recognized in the income statement from the hedging ineffectiveness of a fair value hedge.

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