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Schedule II - Condensed Financial Information of Registrant (Parent Company Only) - Condensed Statements of Stockholders' Equity (Detail) (USD $) In Thousands, unless otherwise specified | 8 Months Ended | 12 Months Ended | 4 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Dec. 31, 2013 | Dec. 31, 2014 | Apr. 30, 2013 | Dec. 31, 2012 | May 01, 2013
Successor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance | $ 460,415 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | $ 978,422 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Issuance of new equity in connection with emergence from Chapter 11 |  |  |  |  | 185,000 us-gaap_PostconfirmationStockholdersEquity / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Total comprehensive income (loss) | 516,904 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 691,884 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Stock-based compensation | 1,106 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 3,450 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired |  | (37)us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Warrants exercised | 16 ambc_WarrantExercisedDuringPeriodValue / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 16 ambc_WarrantExercisedDuringPeriodValue / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired | 19 us-gaap_TreasuryStockValueAcquiredCostMethod / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |  |
Ending balance | 978,422 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,673,735 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Predecessor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance |  |  | (3,246,967)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (3,149,533)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Total comprehensive income (loss) |  |  | 3,522,382 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (97,434)us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Stock-based compensation |  |  | (60)us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (664)us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Cost of shares acquired |  |  | 60 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 664 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Elimination of Predecessor Ambac Shareholder equity accounts |  |  | 0 us-gaap_TemporaryEquityEliminationAsPartofReorganization / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |  |
Ending balance |  |  | 275,415 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (3,246,967)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Retained Earnings/Accumulated Deficit [Member] | Successor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 505,219 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Issuance of new equity in connection with emergence from Chapter 11 |  |  |  |  | 0 us-gaap_PostconfirmationStockholdersEquity / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Total comprehensive income (loss) | 505,219 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 484,071 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Stock-based compensation | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Warrants exercised | 0 ambc_WarrantExercisedDuringPeriodValue / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_WarrantExercisedDuringPeriodValue / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired | 0 us-gaap_TreasuryStockValueAcquiredCostMethod / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |  |
Ending balance | 505,219 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 989,290 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Retained Earnings/Accumulated Deficit [Member] | Predecessor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance |  |  | (6,297,264)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (6,039,922)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Total comprehensive income (loss) |  |  | 3,349,049 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (256,678)us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Stock-based compensation |  |  | (60)us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (664)us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Cost of shares acquired |  |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Elimination of Predecessor Ambac Shareholder equity accounts |  |  | (2,948,275)us-gaap_TemporaryEquityEliminationAsPartofReorganization / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |  |
Ending balance |  |  | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (6,297,264)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Accumulated Other Comprehensive Income (Loss) [Member] | Successor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 11,661 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Issuance of new equity in connection with emergence from Chapter 11 |  |  |  |  | 0 us-gaap_PostconfirmationStockholdersEquity / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Total comprehensive income (loss) | 11,661 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 208,622 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Stock-based compensation | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Warrants exercised | 0 ambc_WarrantExercisedDuringPeriodValue / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_WarrantExercisedDuringPeriodValue / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired | 0 us-gaap_TreasuryStockValueAcquiredCostMethod / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |  |
Ending balance | 11,661 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 220,283 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Accumulated Other Comprehensive Income (Loss) [Member] | Predecessor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance |  |  | 625,385 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 463,259 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Total comprehensive income (loss) |  |  | 174,875 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 162,126 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Stock-based compensation |  |  | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Cost of shares acquired |  |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Elimination of Predecessor Ambac Shareholder equity accounts |  |  | 800,260 us-gaap_TemporaryEquityEliminationAsPartofReorganization / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |  |
Ending balance |  |  | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 625,385 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Preferred Stock [Member] | Successor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Issuance of new equity in connection with emergence from Chapter 11 |  |  |  |  | 0 us-gaap_PostconfirmationStockholdersEquity / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Total comprehensive income (loss) | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Stock-based compensation | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Warrants exercised | 0 ambc_WarrantExercisedDuringPeriodValue / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_WarrantExercisedDuringPeriodValue / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired | 0 us-gaap_TreasuryStockValueAcquiredCostMethod / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |  |
Ending balance | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Preferred Stock [Member] | Predecessor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance |  |  | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Total comprehensive income (loss) |  |  | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Stock-based compensation |  |  | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Cost of shares acquired |  |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Elimination of Predecessor Ambac Shareholder equity accounts |  |  | 0 us-gaap_TemporaryEquityEliminationAsPartofReorganization / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |  |
Ending balance |  |  | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Common Stock [Member] | Successor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance | 450 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 450 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Issuance of new equity in connection with emergence from Chapter 11 |  |  |  |  | 450 us-gaap_PostconfirmationStockholdersEquity / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Total comprehensive income (loss) | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Stock-based compensation | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Warrants exercised | 0 ambc_WarrantExercisedDuringPeriodValue / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_WarrantExercisedDuringPeriodValue / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired | 0 us-gaap_TreasuryStockValueAcquiredCostMethod / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |  |
Ending balance | 450 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 450 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Common Stock [Member] | Predecessor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance |  |  | 3,080 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 3,080 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Total comprehensive income (loss) |  |  | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Stock-based compensation |  |  | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Cost of shares acquired |  |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Elimination of Predecessor Ambac Shareholder equity accounts |  |  | 3,080 us-gaap_TemporaryEquityEliminationAsPartofReorganization / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |  |
Ending balance |  |  | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 3,080 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Additional Paid-in Capital [Member] | Successor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance | 184,550 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 185,672 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Issuance of new equity in connection with emergence from Chapter 11 |  |  |  |  | 184,550 us-gaap_PostconfirmationStockholdersEquity / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Total comprehensive income (loss) | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Stock-based compensation | 1,106 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 3,450 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Warrants exercised | 16 ambc_WarrantExercisedDuringPeriodValue / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 16 ambc_WarrantExercisedDuringPeriodValue / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired | 0 us-gaap_TreasuryStockValueAcquiredCostMethod / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |  |
Ending balance | 185,672 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 189,138 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Additional Paid-in Capital [Member] | Predecessor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance |  |  | 2,172,027 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 2,172,027 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Total comprehensive income (loss) |  |  | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Stock-based compensation |  |  | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Cost of shares acquired |  |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Elimination of Predecessor Ambac Shareholder equity accounts |  |  | 2,172,027 us-gaap_TemporaryEquityEliminationAsPartofReorganization / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |  |
Ending balance |  |  | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 2,172,027 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Common Stock Held in Treasury, at Cost [Member] | Successor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (19)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Issuance of new equity in connection with emergence from Chapter 11 |  |  |  |  | 0 us-gaap_PostconfirmationStockholdersEquity / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Total comprehensive income (loss) | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Stock-based compensation | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired |  | (37)us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Warrants exercised | 0 ambc_WarrantExercisedDuringPeriodValue / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_WarrantExercisedDuringPeriodValue / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired | 19 us-gaap_TreasuryStockValueAcquiredCostMethod / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |  |
Ending balance | (19)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (56)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Common Stock Held in Treasury, at Cost [Member] | Predecessor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance |  |  | (410,755)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (411,419)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Total comprehensive income (loss) |  |  | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Stock-based compensation |  |  | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Cost of shares acquired |  |  | 60 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 664 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Elimination of Predecessor Ambac Shareholder equity accounts |  |  | (410,695)us-gaap_TemporaryEquityEliminationAsPartofReorganization / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |  |
Ending balance |  |  | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (410,755)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Ambac Financial Group, Inc Parent Company Only [Member] | Successor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance | 185,000 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 702,983 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Issuance of new equity in connection with emergence from Chapter 11 |  |  |  |  | 185,000 us-gaap_PostconfirmationStockholdersEquity / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Total comprehensive income (loss) | 516,880 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 692,693 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Stock-based compensation | 1,106 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 3,450 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired |  | (37)us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Warrants exercised | 16 ambc_WarrantExercisedDuringPeriodValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 16 ambc_WarrantExercisedDuringPeriodValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired | (19)us-gaap_TreasuryStockValueAcquiredCostMethod / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |  |
Ending balance | 702,983 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,399,105 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Ambac Financial Group, Inc Parent Company Only [Member] | Predecessor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance |  |  | (3,907,527)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (3,812,975)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Total comprehensive income (loss) |  |  | 3,523,924 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (94,552)us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Stock-based compensation |  |  | 60 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 664 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Cost of shares acquired |  |  | 60 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 664 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Elimination of Predecessor Ambac Shareholder equity accounts |  |  | 383,603 us-gaap_TemporaryEquityEliminationAsPartofReorganization / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |  |
Ending balance |  |  | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (3,907,527)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Ambac Financial Group, Inc Parent Company Only [Member] | Retained Earnings/Accumulated Deficit [Member] | Successor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 505,219 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Issuance of new equity in connection with emergence from Chapter 11 |  |  |  |  | 0 us-gaap_PostconfirmationStockholdersEquity / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Total comprehensive income (loss) | 505,219 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 484,071 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Stock-based compensation | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Warrants exercised | 0 ambc_WarrantExercisedDuringPeriodValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_WarrantExercisedDuringPeriodValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired | 0 us-gaap_TreasuryStockValueAcquiredCostMethod / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |  |
Ending balance | 505,219 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 989,290 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Ambac Financial Group, Inc Parent Company Only [Member] | Retained Earnings/Accumulated Deficit [Member] | Predecessor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance |  |  | (6,297,264)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (6,039,922)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Total comprehensive income (loss) |  |  | 3,349,049 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (256,678)us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Stock-based compensation |  |  | 60 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 664 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Cost of shares acquired |  |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Elimination of Predecessor Ambac Shareholder equity accounts |  |  | 2,948,275 us-gaap_TemporaryEquityEliminationAsPartofReorganization / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |  |
Ending balance |  |  | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (6,297,264)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_RetainedEarningsMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Ambac Financial Group, Inc Parent Company Only [Member] | Accumulated Other Comprehensive Income (Loss) [Member] | Successor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 11,661 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Issuance of new equity in connection with emergence from Chapter 11 |  |  |  |  | 0 us-gaap_PostconfirmationStockholdersEquity / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Total comprehensive income (loss) | 11,661 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 208,622 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Stock-based compensation | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Warrants exercised | 0 ambc_WarrantExercisedDuringPeriodValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_WarrantExercisedDuringPeriodValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired | 0 us-gaap_TreasuryStockValueAcquiredCostMethod / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |  |
Ending balance | 11,661 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 220,283 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Ambac Financial Group, Inc Parent Company Only [Member] | Accumulated Other Comprehensive Income (Loss) [Member] | Predecessor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance |  |  | 625,385 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 463,259 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Total comprehensive income (loss) |  |  | 174,875 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 162,126 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Stock-based compensation |  |  | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Cost of shares acquired |  |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Elimination of Predecessor Ambac Shareholder equity accounts |  |  | (800,260)us-gaap_TemporaryEquityEliminationAsPartofReorganization / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |  |
Ending balance |  |  | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 625,385 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Ambac Financial Group, Inc Parent Company Only [Member] | Preferred Stock [Member] | Successor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Issuance of new equity in connection with emergence from Chapter 11 |  |  |  |  | 0 us-gaap_PostconfirmationStockholdersEquity / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Total comprehensive income (loss) | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Stock-based compensation | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Warrants exercised | 0 ambc_WarrantExercisedDuringPeriodValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_WarrantExercisedDuringPeriodValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired | 0 us-gaap_TreasuryStockValueAcquiredCostMethod / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |  |
Ending balance | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Ambac Financial Group, Inc Parent Company Only [Member] | Preferred Stock [Member] | Predecessor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance |  |  | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Total comprehensive income (loss) |  |  | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Stock-based compensation |  |  | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Cost of shares acquired |  |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Elimination of Predecessor Ambac Shareholder equity accounts |  |  | 0 us-gaap_TemporaryEquityEliminationAsPartofReorganization / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |  |
Ending balance |  |  | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_PreferredStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Ambac Financial Group, Inc Parent Company Only [Member] | Common Stock [Member] | Successor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance | 450 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 450 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Issuance of new equity in connection with emergence from Chapter 11 |  |  |  |  | 450 us-gaap_PostconfirmationStockholdersEquity / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Total comprehensive income (loss) | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Stock-based compensation | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Warrants exercised | 0 ambc_WarrantExercisedDuringPeriodValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_WarrantExercisedDuringPeriodValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired | 0 us-gaap_TreasuryStockValueAcquiredCostMethod / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |  |
Ending balance | 450 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 450 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Ambac Financial Group, Inc Parent Company Only [Member] | Common Stock [Member] | Predecessor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance |  |  | 3,080 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 3,080 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Total comprehensive income (loss) |  |  | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Stock-based compensation |  |  | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Cost of shares acquired |  |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Elimination of Predecessor Ambac Shareholder equity accounts |  |  | (3,080)us-gaap_TemporaryEquityEliminationAsPartofReorganization / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |  |
Ending balance |  |  | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 3,080 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Ambac Financial Group, Inc Parent Company Only [Member] | Additional Paid-in Capital [Member] | Successor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance | 184,550 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 185,672 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Issuance of new equity in connection with emergence from Chapter 11 |  |  |  |  | 184,550 us-gaap_PostconfirmationStockholdersEquity / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Total comprehensive income (loss) | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Stock-based compensation | 1,106 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 3,450 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Warrants exercised | 16 ambc_WarrantExercisedDuringPeriodValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 16 ambc_WarrantExercisedDuringPeriodValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired | 0 us-gaap_TreasuryStockValueAcquiredCostMethod / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |  |
Ending balance | 185,672 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 189,138 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Ambac Financial Group, Inc Parent Company Only [Member] | Additional Paid-in Capital [Member] | Predecessor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance |  |  | 2,172,027 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 2,172,027 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Total comprehensive income (loss) |  |  | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Stock-based compensation |  |  | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Cost of shares acquired |  |  | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Elimination of Predecessor Ambac Shareholder equity accounts |  |  | (2,172,027)us-gaap_TemporaryEquityEliminationAsPartofReorganization / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |  |
Ending balance |  |  | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 2,172,027 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AdditionalPaidInCapitalMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Ambac Financial Group, Inc Parent Company Only [Member] | Common Stock Held in Treasury, at Cost [Member] | Successor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance | 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (19)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Issuance of new equity in connection with emergence from Chapter 11 |  |  |  |  | 0 us-gaap_PostconfirmationStockholdersEquity / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Total comprehensive income (loss) | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Stock-based compensation | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired |  | (37)us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Warrants exercised | 0 ambc_WarrantExercisedDuringPeriodValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_WarrantExercisedDuringPeriodValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Cost of shares acquired | (19)us-gaap_TreasuryStockValueAcquiredCostMethod / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |  |
Ending balance | (19)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (56)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Ambac Financial Group, Inc Parent Company Only [Member] | Common Stock Held in Treasury, at Cost [Member] | Predecessor [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Beginning balance |  |  | (410,755)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | (411,419)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Total comprehensive income (loss) |  |  | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Stock-based compensation |  |  | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 0 us-gaap_AllocatedShareBasedCompensationExpense / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Cost of shares acquired |  |  | 60 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | 664 us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |
Elimination of Predecessor Ambac Shareholder equity accounts |  |  | 410,695 us-gaap_TemporaryEquityEliminationAsPartofReorganization / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |  |
Ending balance |  |  | $ 0 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember | $ (410,755)us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember / us-gaap_StatementEquityComponentsAxis = us-gaap_TreasuryStockMember / us-gaap_StatementScenarioAxis = us-gaap_PredecessorMember |

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