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Insurance Regulations And Dividends (Narrative) (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Insurance Regulations And Dividends [Line Items] |  |  |
Percentage of policyholders' surplus | 10.00% |  |
Percentage of adjusted net investment income | 100.00% |  |
Policyholders Surplus [Member] | Minimum [Member] |  |  |
Insurance Regulations And Dividends [Line Items] |  |  |
Policyholders' surplus | $ 65 |  |
MBIA Corp [Member] |  |  |
Insurance Regulations And Dividends [Line Items] |  |  |
Unassigned surplus | 1,900 | $ 1,900 |
Statutory net loss |  | 129 | $ 202
Statutory capital | 169 | 134 |
Policyholders' surplus | 164 |  |
Contingency reserves | 5 |  |
Statutory net income | 46 |  |
National [Member] |  |  |
Insurance Regulations And Dividends [Line Items] |  |  |
Dividends from subsidiaries | 72 | 60 | 81
Statutory net loss |  |  | $ 82
Statutory capital | 1,900 | 2,000 |
Policyholders' surplus | 1,500 |  |
Contingency reserves | 379 |  |
Statutory net income | $ 75 | $ 55 |

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- Definition This element represents disclosure of the aggregate cash dividends paid to the entity by consolidated subsidiaries. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04(b)) -URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e24072-122690 + Details
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