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Derivatives - Gain (loss) included in the Statement of Earnings for changes in the fair value of derivatives that do not qualify for hedge accounting (Details) - Not Designated as Hedging Instrument - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		$ (103)	$ (80)	$ (83)
MBS with embedded derivatives | Realized gains (losses) on securities
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		(6)	(9)	(16)
Public company warrants | Realized gains (losses) on securities
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		0	0	0
Fixed-indexed annuities (embedded derivative) | Annuity benefits
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	[1]	(589)	(211)	(17)
Equity index call options | Annuity benefits
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		494	141	(56)
Reinsurance contract (embedded derivative) | Net investment income
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		$ (2)	$ (1)	$ 6
[1] The change in fair value of the embedded derivative includes losses related to unlocking of actuarial assumptions of $25 million in 2017 compared to $17 million in 2016 and $28 million in 2015.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a),(c),(d),(e)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

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