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Investments - Allowance for credit losses on fixed maturities (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2021 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020 | Jan. 01, 2020
Allowance for Credit Losses [Roll Forward] |  |  |  |  |
Beginning balance | $ 10 | $ 14 | $ 12 | $ 0 |
Impact of adoption of new accounting policy | 9 | 14 | 9 | 14 |
Initial allowance for purchased securities with credit deterioration | 0 | 0 | 0 | 0 |
Provision for expected credit losses on securities with no previous allowance | 0 | 2 | 0 | 16 |
Additions (reductions) to previously recognized expected credit losses | 0 | (2) | (1) | (2) |
Reductions due to sales or redemptions | (1) | 0 | (2) | 0 |
Ending balance | 9 | 14 | 9 | 14 |
Structured securities |  |  |  |  |
Allowance for Credit Losses [Roll Forward] |  |  |  |  |
Beginning balance | 9 | 11 | 10 | 0 |
Impact of adoption of new accounting policy | 8 | 11 | 8 | 11 | $ 0
Initial allowance for purchased securities with credit deterioration | 0 | 0 | 0 | 0 |
Provision for expected credit losses on securities with no previous allowance | 0 | 1 | 0 | 12 |
Additions (reductions) to previously recognized expected credit losses | (1) | (1) | (2) | (1) |
Reductions due to sales or redemptions | 0 | 0 | 0 | 0 |
Ending balance | 8 | 11 | 8 | 11 |
Corporate and other |  |  |  |  |
Allowance for Credit Losses [Roll Forward] |  |  |  |  |
Beginning balance | 1 | 3 | 2 | 0 |
Impact of adoption of new accounting policy | 1 | 3 | 1 | 3 | 0
Initial allowance for purchased securities with credit deterioration | 0 | 0 | 0 | 0 |
Provision for expected credit losses on securities with no previous allowance | 0 | 1 | 0 | 4 |
Additions (reductions) to previously recognized expected credit losses | 1 | (1) | 1 | (1) |
Reductions due to sales or redemptions | (1) | 0 | (2) | 0 |
Ending balance | $ 1 | $ 3 | $ 1 | $ 3 |
Accounting Standards Update 2016-13 |  |  |  |  |
Allowance for Credit Losses [Roll Forward] |  |  |  |  |
Impact of adoption of new accounting policy |  |  |  |  | $ 0

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- Definition Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 9 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aaa) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 + Details
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- Definition Amount of expense for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), for which no credit loss was previously recorded. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 9 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455 + Details
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- Definition Amount of expense (reversal of expense) for allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), not intended to be sold and not more likely than not will be required to sell before recovery of amortized cost basis, with previously recorded allowance. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 9 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455 + Details
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- Definition Amount of increase in allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) and beneficial interest, purchased with credit deterioration. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 9 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455 + Details
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- Definition Amount of decrease in allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) from sale. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 9 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455 + Details
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