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v3.20.2

Variable Interest Entities (Narrative) (Detail) $ in Millions | 1 Months Ended | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Oct. 31, 2020 USD ($) issue | Mar. 31, 2020 | Jun. 30, 2019 USD ($) | Mar. 31, 2019 USD ($) | Dec. 31, 2019 USD ($) | Sep. 30, 2020 USD ($)
Variable Interest Entity [Line Items] |  |  |  |  |  |
Carrying amounts of assets |  |  |  |  | $ 7,284 | $ 6,551
Carrying amounts of liabilities |  |  |  |  | 6,445 | 6,308
Additional Voluntary Payment |  |  |  |  | 66 |
Variable Interest Entity Primary Beneficiary [Member] |  |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |  |
Carrying amounts of assets |  |  |  |  | 1,600 | 1,300
Carrying amounts of liabilities |  |  |  |  | $ 1,500 | $ 1,200
Variable Interest Entity Primary Beneficiary [Member] | Subsequent Event [Member] |  |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |  |
Number of variable interest entities deconsolidated | issue | 1 |  |  |  |  |
Reduction in Variable Interest Entities assets and liabilities | $ 575 |  |  |  |  |
Variable Interest Entity Primary Beneficiary [Member] | U S Public Finance Insurance [Member] |  |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |  |
Number of variable interest entities deconsolidated |  | 7 |  |  |  |
Number of variable interest entities consolidated |  |  |  | 7 |  |
Net realized gains (losses) related to the initial consolidation |  |  |  | $ (42) |  |
Variable Interest Entity Primary Beneficiary [Member] | Structured Finance And International Insurance [Member] |  |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |  |
Number of variable interest entities deconsolidated |  | 1 | 2 |  |  |
Deconsolidation, Gain (Loss), Amount |  |  | $ (16) |  |  |

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- Definition Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(11)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(g)(1)(ii)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 28 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (bb) -URI http://asc.fasb.org/extlink&oid=121559654&loc=d3e5710-111685 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 25 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=116870748&loc=SL6758485-165988 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 32 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599 Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(12)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 30 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599 + Details
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