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Fair Value Measurements - Information about Valuation Inputs for Fixed Income Securities Classified as Level 3 (Detail) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2013 | Dec. 31, 2012
Corporate obligations [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Coupon rate | 0.345% | 0.345%
Maturity | 20 years 10 months 21 days | 21 years 1 month 21 days
Yield | 6.03% | 6.08%
Collateralized debt obligations [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Coupon rate | 0.85% | 1.05%
Maturity | 1 year 2 months 27 days | 1 year 6 months 4 days
Yield | 3.85% | 5.92%
Other commercial asset-backed [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Coupon rate | 0.69% | 0.71%
Maturity | 7 years 7 months 13 days | 7 years 10 months 10 days
Yield | 7.50% | 7.50%
European ABS transactions [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Coupon rate | 1.59% | 1.64%
Maturity | 18 years 3 months 4 days | 12 years 4 months 2 days
Yield | 3.98% | 4.02%

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- Definition Fair value inputs coupon rate. + References No definition available. + Details
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- Definition Fair value inputs maturity. + References No definition available. + Details
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- Definition Fair value inputs yield. + References No definition available. + Details
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Namespace Prefix: | ambc_
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- Details
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