XML 142 R122.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Schedule II - Condensed Financial Information of Registrant (Parent Company Only) - Condensed Statements of Stockholders' Equity (Detail) - USD ($) $ in Thousands | 12 Months Ended | 18 Months Ended |
--- | --- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2016 | Dec. 31, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Total comprehensive income (loss) | $ 273,823 | $ (335,376) | $ 20,112 |  |
Stock-based compensation | (11,854) | (4,293) | (5,253) |  |
Cost of shares (acquired) issued under equity plan | (1,158) | (1,547) | (505) |  |
Payments for Repurchase of Warrants |  |  | 2,717 | $ 8,092 |
Stock Issued During Period, Value, New Issues | 1 | 1 | 2 |  |
Noncontrolling Interest, Decrease from Deconsolidation |  |  | (2,469) |  |
Proceeds from Warrant Exercises | 3 | 0 | 2 |  |
AMPS Impact on Stockholders Equity | (296,634) |  |  |  |
Ending balance | 1,633,147 | 1,645,258 | 1,978,024 | 1,978,024 |
Stockholders' Equity Attributable to Parent | 1,591,997 | 1,381,148 |  |  |
Retained Earnings [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Total comprehensive income (loss) | 267,399 | (328,715) | 74,843 |  |
Cost of shares (acquired) issued under equity plan | (1,156) | (1,572) | (127) |  |
Payments for Repurchase of Warrants |  |  | 1,916 |  |
Stock Issued During Period, Value, New Issues | 0 | 0 |  |  |
AMPS Impact on Stockholders Equity | (81,686) |  |  |  |
Ending balance | 1,421,302 | 1,233,845 | 1,557,681 | 1,557,681 |
AOCI Attributable to Parent [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Total comprehensive income (loss) | 6,424 | (6,661) | (54,205) |  |
Stock Issued During Period, Value, New Issues | 0 | 0 |  |  |
Ending balance | (48,715) | (52,239) | (38,990) | (38,990) |
Preferred Stock [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Stock Issued During Period, Value, New Issues |  | 0 |  |  |
Ending balance | 0 | 0 | 0 | 0 |
Common Stock [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Stock Issued During Period, Value, New Issues | 1 | 1 | 2 |  |
Proceeds from Warrant Exercises | 0 |  | 0 |  |
Ending balance | 454 | 453 | 452 | 452 |
Additional Paid-in Capital [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Stock-based compensation | (11,854) | (4,293) | (5,253) |  |
Payments for Repurchase of Warrants |  |  | 801 |  |
Stock Issued During Period, Value, New Issues | 0 | 0 | 0 |  |
Proceeds from Warrant Exercises | 3 |  | 2 |  |
AMPS Impact on Stockholders Equity | 8,012 |  |  |  |
Ending balance | 219,429 | 199,560 | 195,267 | 195,267 |
Common Stock Held in Treasury, at Cost [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Cost of shares (acquired) issued under equity plan | (2) | 25 | (378) |  |
Proceeds from Warrant Exercises | 0 |  |  |  |
Ending balance | (473) | (471) | (496) | (496) |
Noncontrolling Interest [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Total comprehensive income (loss) | 0 | 0 | (526) |  |
Noncontrolling Interest, Decrease from Deconsolidation |  |  | (2,469) |  |
AMPS Impact on Stockholders Equity | (222,960) |  |  |  |
Ending balance | 41,150 | 264,110 | 264,110 | 264,110 |
Ambac Financial Group, Inc Parent Company Only [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Total comprehensive income (loss) | 192,137 | (335,376) | 20,638 |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | 0 | (137) | 6,442 |  |
Stock-based compensation | (11,854) | (4,293) | (5,253) |  |
Cost of shares (acquired) issued under equity plan | (1,158) | (1,547) | (505) |  |
Payments for Repurchase of Warrants | 0 | 0 | (2,717) |  |
Stock Issued During Period, Value, New Issues | 1 | 1 | 2 |  |
Proceeds from Warrant Exercises | 3 | 0 | 2 |  |
AMPS Impact on Stockholders Equity | 8,012 |  |  |  |
Stockholders' Equity Attributable to Parent | 1,591,997 | 1,381,148 | 1,713,914 | 1,713,914 | $ 1,684,799
Ambac Financial Group, Inc Parent Company Only [Member] | Retained Earnings [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Total comprehensive income (loss) | 185,713 | (328,715) | 74,843 |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification |  | (137) | 6,442 |  |
Cost of shares (acquired) issued under equity plan | (1,156) | (1,572) | (127) |  |
Payments for Repurchase of Warrants |  |  | (1,916) |  |
AMPS Impact on Stockholders Equity | 0 |  |  |  |
Stockholders' Equity Attributable to Parent | 1,421,302 | 1,233,845 | 1,557,681 | 1,557,681 | 1,478,439
Ambac Financial Group, Inc Parent Company Only [Member] | AOCI Attributable to Parent [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Total comprehensive income (loss) | 6,424 | (6,661) | (54,205) |  |
Stockholders' Equity Attributable to Parent | (48,715) | (52,239) | (38,990) | (38,990) | 15,215
Ambac Financial Group, Inc Parent Company Only [Member] | Preferred Stock [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Stockholders' Equity Attributable to Parent | 0 | 0 | 0 | 0 | 0
Ambac Financial Group, Inc Parent Company Only [Member] | Common Stock [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Stock Issued During Period, Value, New Issues | 1 | 1 | 2 |  |
Proceeds from Warrant Exercises | 0 |  | 0 |  |
Stockholders' Equity Attributable to Parent | 454 | 453 | 452 | 452 | 450
Ambac Financial Group, Inc Parent Company Only [Member] | Additional Paid-in Capital [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Stock-based compensation | (11,854) | (4,293) | (5,253) |  |
Payments for Repurchase of Warrants |  |  | (801) |  |
Stock Issued During Period, Value, New Issues | 0 | 0 | 0 |  |
Proceeds from Warrant Exercises | 3 |  | 2 |  |
AMPS Impact on Stockholders Equity | 8,012 |  |  |  |
Stockholders' Equity Attributable to Parent | 219,429 | 199,560 | 195,267 | 195,267 | 190,813
Ambac Financial Group, Inc Parent Company Only [Member] | Common Stock Held in Treasury, at Cost [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
Stock-based compensation |  | 0 |  |  |
Cost of shares (acquired) issued under equity plan | (2) | 25 | (378) |  |
Proceeds from Warrant Exercises |  |  | 0 |  |
Stockholders' Equity Attributable to Parent | (473) | (471) | (496) | $ (496) | $ (118)
Accounting Standards Update 2014-13 [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification |  |  | 0 |  |
Accounting Standards Update 2014-13 [Member] | Retained Earnings [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification |  |  | 6,442 |  |
Accounting Standards Update 2014-13 [Member] | Noncontrolling Interest [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification |  |  | $ (6,442) |  |
Accounting Standards Update 2016-01 [Member] | Retained Earnings [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | 2,900 |  |  |  |
Accounting Standards Update 2016-01 [Member] | AOCI Attributable to Parent [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | $ (2,900) |  |  |  |
Accounting Standards Update 2018-02 [Domain] | AOCI Attributable to Parent [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification |  | (6,588) |  |  |
Accounting Standards Update 2018-02 [Domain] | Ambac Financial Group, Inc Parent Company Only [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification |  | 0 |  |  |
Accounting Standards Update 2018-02 [Domain] | Ambac Financial Group, Inc Parent Company Only [Member] | Retained Earnings [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification |  | 6,588 |  |  |
Accounting Standards Update 2018-02 [Domain] | Ambac Financial Group, Inc Parent Company Only [Member] | AOCI Attributable to Parent [Member] |  |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification |  | $ (6,588) |  |  |

X
- Definition AMPS Impact on Stockholders Equity + References No definition available. + Details
Name: | ambc_AMPSImpactonStockholdersEquity
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5047-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.F) -URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_AllocatedShareBasedCompensationExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 55 -Paragraph 4K -URI http://asc.fasb.org/extlink&oid=84234705&loc=SL4591552-111686 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1A -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669619-108580 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 19 -URI http://asc.fasb.org/extlink&oid=108774443&loc=SL4569616-111683 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1B -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669625-108580 + Details
Name: | us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_IncreaseDecreaseInStockholdersEquityRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements. + References No definition available. + Details
Name: | us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of the reduction or elimination during the period of a noncontrolling interest resulting from the parent's loss of control and deconsolidation of the entity in which one or more outside parties had a noncontrolling interest. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=109239629&loc=SL4573702-111684 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
Name: | us-gaap_NoncontrollingInterestDecreaseFromDeconsolidation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The aggregate amount paid by the entity to reacquire the right to purchase equity shares at a predetermined price, usually issued together with corporate debt. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3291-108585 + Details
Name: | us-gaap_PaymentsForRepurchaseOfWarrants
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash inflow associated with the amount received from holders exercising their stock warrants. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromWarrantExercises
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_StockIssuedDuringPeriodValueNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Value of stock (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of stock value of such awards forfeited. Stock issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5047-113901 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SAB Topic 4.E) -URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74512-122707 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(31)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(30)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_StockholdersEquity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 16 -URI http://asc.fasb.org/extlink&oid=108774443&loc=SL4568740-111683 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 55 -Paragraph 4I -URI http://asc.fasb.org/extlink&oid=84234705&loc=SL4590271-111686 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=108774443&loc=SL4568447-111683 + Details
Name: | us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_RetainedEarningsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedOtherComprehensiveIncomeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_PreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_CommonStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AdditionalPaidInCapitalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_TreasuryStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_NoncontrollingInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=srt_ParentCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis=us-gaap_AccountingStandardsUpdate201413Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis=us-gaap_AccountingStandardsUpdate201601Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis=ambc_AccountingStandardsUpdate201802Domain
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |