Derivatives (Fair Value Hedges) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Components Excluded from Assessment of Foreign Currency Fair Value Hedge Effectiveness	$ (12)	$ (17)	$ (20)	$ (24)
Net Derivative Gains (Losses) Recognized for Derivatives	(125)	71	(165)	64
Net Derivative Gains (Losses) Recognized for Hedged Items	121	16	172	29
Ineffectiveness Recognized in Net Derivative Gains (Losses)	(4)	87	7	93
Interest rate swaps \| Fixed Maturity Securities
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	0	3	1
Net Derivative Gains (Losses) Recognized for Hedged Items	0	(1)	(2)	(2)
Ineffectiveness Recognized in Net Derivative Gains (Losses)	0	(1)	1	(1)
Interest rate swaps \| Policyholder account balances
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(68)	49	(281)	(2)
Net Derivative Gains (Losses) Recognized for Hedged Items	70	21	282	71
Ineffectiveness Recognized in Net Derivative Gains (Losses)	2	70	1	69
Foreign currency swaps \| Foreign-denominated fixed maturity securities and mortgage loans
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	52	(2)	25	(5)
Net Derivative Gains (Losses) Recognized for Hedged Items	(53)	3	(26)	6
Ineffectiveness Recognized in Net Derivative Gains (Losses)	(1)	1	(1)	1
Foreign currency swaps \| Foreign-denominated policyholder account balances [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	5	45	23	46
Net Derivative Gains (Losses) Recognized for Hedged Items	(5)	(26)	(23)	(24)
Ineffectiveness Recognized in Net Derivative Gains (Losses)	0	19	0	22
Foreign currency forwards \| Foreign-denominated fixed maturity securities and mortgage loans
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(114)	(21)	65	24
Net Derivative Gains (Losses) Recognized for Hedged Items	109	19	(59)	(22)
Ineffectiveness Recognized in Net Derivative Gains (Losses)	$ (5)	$ (2)	$ 6	$ 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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-Publisher FASB
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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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