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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 | 3 Months Ended | 9 Months Ended
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Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017
Derivative, Gain (Loss) on Derivative, Net [Abstract] |  |  |  |  |
Derivative |  | $ (6) | $ (12) | $ (21) | $ (54)
MBS with embedded derivatives | Realized gains (losses) on securities |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net [Abstract] |  |  |  |  |
Derivative |  | (3) | 0 | (8) | (3)
Public company warrants | Realized gains (losses) on securities |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net [Abstract] |  |  |  |  |
Derivative |  | 1 | (1) | 0 | (1)
Fixed-indexed and variable-indexed annuities (embedded derivative) | Annuity benefits |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net [Abstract] |  |  |  |  |
Derivative | [1] | (223) | (127) | (286) | (386)
Equity index call options | Annuity benefits |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net [Abstract] |  |  |  |  |
Derivative |  | 219 | 116 | 271 | 338
Equity index put options | Annuity benefits |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net [Abstract] |  |  |  |  |
Derivative |  | 0 | 0 | 0 | 0
Reinsurance contracts (embedded derivative) | Net investment income |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net [Abstract] |  |  |  |  |
Derivative |  | $ 0 | $ 0 | $ 2 | $ (2)
[1] | The change in fair value of the embedded derivative for the nine months ended September 30, 2018 includes a $44 million charge in the second quarter of 2018 related to the unlocking of actuarial assumptions.

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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/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959 + Details
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