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Investments - Holding gains (losses) on equity securities still held (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Holding Gains (Losses) on Equity Securities Still Held [Line Items] |  |  |  |
Realized gains (losses) on securities still owned | $ 31 | $ 8 | $ (62) | $ 11
Included in net investment income | 535 | 464 | 1,035 | 904
Equity securities |  |  |  |
Holding Gains (Losses) on Equity Securities Still Held [Line Items] |  |  |  |
Realized gains (losses) on securities still owned | 23 | $ (3) | (72) | $ (10)
Equity securities still owned | Equity securities | Accounting Standards Update 2016-01 |  |  |  |
Holding Gains (Losses) on Equity Securities Still Held [Line Items] |  |  |  |
Net holding gains (losses) on equity securities | 31 |  | (57) |
Equity securities still owned | Realized gains (losses) on securities | Equity securities | Accounting Standards Update 2016-01 |  |  |  |
Holding Gains (Losses) on Equity Securities Still Held [Line Items] |  |  |  |
Realized gains (losses) on securities still owned | 16 |  | (71) |
Equity securities still owned | Investment income | Equity securities | Accounting Standards Update 2016-01 |  |  |  |
Holding Gains (Losses) on Equity Securities Still Held [Line Items] |  |  |  |
Included in net investment income | $ 15 |  | $ 14 |

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- Definition holding gains (losses) on equity securities still held + References No definition available. + Details
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- Definition Net holding gains (losses) on equity securities in net earnings on securities that were still owned. All equity securities other than those accounted for under the equity method are carried at fair value through net earnings. + References No definition available. + Details
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- Definition Amount, before investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.2) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 + Details
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- Definition This item represents the total realized gain (loss) included in earnings for the period as a result of selling marketable securities categorized as trading, available-for-sale, or held-to-maturity. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(c)) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27405-111563 + Details
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