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Insurance Regulations And Dividends (Narrative) (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017
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 | $ (1,700) | $ (1,800)
Percentage of loss reserves and unearned premium reserve required to be invested in qualifying assets | 50.00% |
Statutory capital | $ 555 | 464
Policyholders' surplus | 356 |
Contingency reserves | 199 |
Statutory net income | 134 | 107
National [Member] |  |
Insurance Regulations And Dividends [Line Items] |  |
Dividends from subsidiaries | 108 | 118
Statutory net loss | 27 | 321
Statutory capital | 2,500 | $ 2,800
Policyholders' surplus | 2,000 |
Contingency reserves | $ 522 |

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- Definition Statutory Accounting Practices defined as policyholders' surplus plus contingency reserves. + References No definition available. + Details
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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 http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 + Details
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