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Outstanding Exposure - Additional Information (Details) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2026 USD ($) category | Dec. 31, 2025 USD ($)
Schedule of Insured Financial Obligations [Line Items] |  |
Number of surveillance categories | category | 3 |
Loss mitigation securities | $ 800 | $ 800
Aircraft residual value insurance (RVI) |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Residual value insurance policies exposure downgraded | 200 | 200
Net Exposure | 100 | 100
Aircraft residual value insurance (RVI) | BIG |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Residual value insurance policies exposure downgraded |  | 5
Net Exposure |  | $ 5
Commitment to Provide Guarantees | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Outstanding commitments to provide guaranties | 1,400 |
Commitment to Provide Guarantees | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Outstanding commitments to provide guaranties | $ 3,500 |
Minimum |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Probability of paying more claims than being reimbursed (as a percent) | 50.00% |

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- Definition Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 942 -SubTopic 235 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147477314/942-235-S99-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480738/235-10-S50-4 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480678/235-10-S99-3 + Details
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