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Investments - Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2017 | Mar. 31, 2016
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |
Realized before impairments | $ 9 | $ 34
Realized — impairments | (6) | (52)
Realized gains (losses) on securities | 3 | (18)
Net of tax and noncontrolling interests |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |
Realized before impairments | 6 | 22
Realized — impairments | (4) | (32)
Realized gains (losses) on securities | 2 | (10)
Change in unrealized | 125 | 134
Total pretax |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |
Realized before impairments | 9 | 34
Realized — impairments | (6) | (52)
Realized gains (losses) on securities | 3 | (18)
Change in unrealized | 191 | 210
Fixed maturities |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |
Realized before impairments | 5 | 14
Realized — impairments | 0 | (16)
Realized gains (losses) on securities | 5 | (2)
Change in unrealized | 202 | 453
Equity securities |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |
Realized before impairments | 2 | 23
Realized — impairments | (9) | (41)
Realized gains (losses) on securities | (7) | (18)
Change in unrealized | 72 | (23)
Mortgage loans and other investments |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |
Realized before impairments | 3 | 0
Realized — impairments | 0 | 0
Realized gains (losses) on securities | 3 | 0
Change in unrealized | 0 | 0
Other, Including DPAC and reserves on annuities and long-term care |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |
Realized before impairments | (1) | (3)
Realized — impairments | 3 | 5
Realized gains (losses) on securities | 2 | 2
Change in unrealized | (83) | (220)
Tax effects |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |
Realized before impairments | (3) | (12)
Realized — impairments | 2 | 19
Realized gains (losses) on securities | (1) | 7
Change in unrealized | (66) | (74)
Noncontrolling interests |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |
Realized before impairments | 0 | 0
Realized — impairments | 0 | 1
Realized gains (losses) on securities | 0 | 1
Change in unrealized | $ 0 | $ (2)

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- Definition Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments. + References No definition available. + 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=73527792&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=73527792&loc=d3e27405-111563 + Details
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- Definition The amount of other than temporary impairment losses on investments in debt and equity securities categorized as Available-for-sale which have been recognized in earnings during the period. Such impairment losses consist of other than temporary impairments (OTTI) on equity securities, credit losses on investments in debt securities, and when the entity intends to sell an impaired debt security or it is more likely than not that the entity will be required to sell the impaired debt security before recovery of its amortized cost basis. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27161-111563 + Details
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