Insurance [Line Items]

No definition available.

Name:	ambc_InsuranceLineItems
Namespace Prefix:	ambc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Past Due Premiums Receivable

+ References

No definition available.

+ Details

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Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The valuation allowance as of the balance sheet date to reduce the gross amount of receivables to estimated net realizable value, which would be presented in parentheses on the face of the balance sheet.

+ References

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Balance Type:	credit
Period Type:	instant

- Definition

This element represents the amount of premium revenue on financial guarantee insurance contracts recognized during the period that was accelerated for revenue recognition purposes.

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Balance Type:	credit
Period Type:	duration

- Definition

Amount of the premium receivable for financial guarantee insurance contracts reported in the statement of financial position. This element primarily would consist of those financial guarantee insurance contracts which premiums are to be collected over the contract period, but may, on occasion, include premiums which are to be collected in full at inception, but which straddle a financial reporting period.

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Balance Type:	debit
Period Type:	instant

- Definition

Amount of cash inflow from premiums received for premium receivable on financial guarantee insurance contracts.

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+ Details

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Period Type:	duration

- 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.

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- Definition

Amount of accretion of the discount for premiums receivable on financial guarantee insurance contracts.

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+ Details

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- Definition

Amount of increase (decrease) in the premium receivable on financial guarantee insurance contracts from changes in the period of the contract.

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- Definition

Amount of increase (decrease) in the premiums receivable on financial guarantee insurance contracts from adjustments classified as other.

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- Definition

Amount of financing receivable 90 days or more past due and still accruing.

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- Definition

Amount of investments classified as other.

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- Definition

Amount of expense (reversal of expense) for expected credit loss on premium receivable.

+ References

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- Definition

The carrying value as of the balance sheet date of the estimated valuation allowance to reduce gross premiums receivable to net realizable value.

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- Definition

Amount of increase (decrease) in allowance for credit loss on premium receivable.

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- Definition

Amount of increase in allowance for credit loss on premium receivable from recovery.

+ References

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- Definition

Amount of writeoff of premium receivable, charged against allowance for credit loss.

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- Definition

The carrying amount as of the balance sheet date due the entity from (a) agents and insureds, (b) uncollected premiums and (c) others, net of the allowance for doubtful accounts.

+ References

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- Definition

Gross amount, as of the balance sheet date, due the entity from (a) agents and insureds, (b) uncollected premiums and (c) others, before deducting the allowance for doubtful accounts.

+ References

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- 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.

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Financial Guarantee Insurance Contracts - Summary of Gross Premium Receivable Roll-Forward (Direct and Assumed Contracts) (Details) $ in Thousands, € in Millions, £ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2022 USD ($)	Sep. 30, 2022 GBP (£)	Sep. 30, 2022 EUR (€)	Sep. 30, 2021 USD ($)	Sep. 30, 2021 GBP (£)	Sep. 30, 2021 EUR (€)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Insurance [Line Items]
Allowance for Doubtful Accounts, Premiums and Other Receivables	$ 6,000			$ 10,000			$ 6,000	$ 10,000	$ 6,000	$ 9,000	$ 11,000	$ 17,000
Financial Guarantee Insurance Contracts, Accelerated Premium Revenue, Amount	(1,735)			0			4,532	0
Past Due Premiums Receivable	49						49			19
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Beginning premium receivable							320,000	370,000
Premium receipts							30,000	28,000
Adjustments for changes in expected and contractual cash flows							(21,000)	(25,000)
Accretion of premium receivable discount							6,000	6,000
Uncollectable premiums							3,000	7,000
Other adjustments (including foreign exchange)							(20,000)	(4,000)
Ending premium receivable	259,000			325,000			259,000	325,000
Premium Receivable, Allowance for Credit Loss	6,000						6,000			9,000
Premium Receivable, Credit Loss Expense (Reversal)	(1,000)			(1,000)			(3,000)	(6,000)
Premium Receivable, Allowance for Credit Loss, Writeoff	0			0			0	(1,000)
Premium Receivable, Allowance for Credit Loss, Recovery	0			0			0	0
Financing Receivable, 90 Days or More Past Due, Still Accruing	34						34			14
Premiums Receivable, Gross	264,000						264,000			329,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,071,000			1,121,000			1,071,000	1,121,000	$ 846,000	1,098,000	$ 1,123,000	$ 1,140,000
Premiums Receivable, Net	268,000						268,000			323,000
Real Estate [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Other investments	34,000						34,000			33,000
Real Estate [Member] \| Foreign Exchange
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Other adjustments (including foreign exchange)							(19,000)	(3,000)
Specialty Property & Casualty Program
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	9,000						9,000			2,000
Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	152,000						152,000			159,000
Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	24,000						24,000			45,000
International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	88,000						88,000			125,000
I/SL [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	222,000						222,000			277,000
I/SL [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	145,000						145,000			151,000
I/SL [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	5,000						5,000			19,000
I/SL [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	72,000						72,000			107,000
IA [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	10,000						10,000			12,000
IA [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	3,000						3,000			3,000
IA [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	1,000						1,000			1,000
IA [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	6,000						6,000			8,000
II [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	5,000						5,000			6,000
II [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	5,000						5,000			5,000
II [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			1,000
II [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
III [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	16,000						16,000			22,000
III [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
III [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	8,000						8,000			12,000
III [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	9,000						9,000			11,000
IV [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	11,000						11,000			12,000
IV [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
IV [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	11,000						11,000			12,000
IV [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
United Kingdom, Pounds
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Ending premium receivable	73,000	£ 66		108,000	£ 80		73,000	108,000
Euro Member Countries, Euro
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Ending premium receivable	14,000		€ 14	$ 16,000		€ 14	14,000	$ 16,000
Other Public Finance Sectors [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	2,000						2,000			2,000
Other Public Finance Sectors [Member] \| I/SL [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	2,000						2,000			2,000
Other Public Finance Sectors [Member] \| IA [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Other Public Finance Sectors [Member] \| II [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Other Public Finance Sectors [Member] \| III [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Other Public Finance Sectors [Member] \| IV [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Other International [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	3,000						3,000			5,000
Other International [Member] \| I/SL [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	3,000						3,000			5,000
Other International [Member] \| IA [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Other International [Member] \| II [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Other International [Member] \| III [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Other International [Member] \| IV [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Mortgage Backed And Home Equity [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	12,000						12,000			16,000
Mortgage Backed And Home Equity [Member] \| I/SL [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			1,000
Mortgage Backed And Home Equity [Member] \| IA [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Mortgage Backed And Home Equity [Member] \| II [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			1,000
Mortgage Backed And Home Equity [Member] \| III [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			2,000
Mortgage Backed And Home Equity [Member] \| IV [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	11,000						11,000			12,000
Structured Insurance [Domain] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross										10,000
Structured Insurance [Domain] \| I/SL [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross										10,000
Structured Insurance [Domain] \| IA [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross										0
Structured Insurance [Domain] \| II [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross										0
Structured Insurance [Domain] \| III [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross										0
Structured Insurance [Domain] \| IV [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross										0
Student Loans [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	9,000						9,000			12,000
Student Loans [Member] \| I/SL [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	1,000						1,000			1,000
Student Loans [Member] \| IA [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	1,000						1,000			1,000
Student Loans [Member] \| II [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Student Loans [Member] \| III [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	7,000						7,000			9,000
Student Loans [Member] \| IV [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Other Structured Finance [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	4,000						4,000			7,000
Other Structured Finance [Member] \| I/SL [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	4,000						4,000			7,000
Other Structured Finance [Member] \| IA [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Other Structured Finance [Member] \| II [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Other Structured Finance [Member] \| III [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Other Structured Finance [Member] \| IV [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Sovereign And Sub Sovereign [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	68,000						68,000			93,000
Sovereign And Sub Sovereign [Member] \| I/SL [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	53,000						53,000			74,000
Sovereign And Sub Sovereign [Member] \| IA [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	6,000						6,000			8,000
Sovereign And Sub Sovereign [Member] \| II [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Sovereign And Sub Sovereign [Member] \| III [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	9,000						9,000			11,000
Sovereign And Sub Sovereign [Member] \| IV [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Investor Owned And Public Utilities [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	16,000						16,000			28,000
Investor Owned And Public Utilities [Member] \| I/SL [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	16,000						16,000			28,000
Investor Owned And Public Utilities [Member] \| IA [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Investor Owned And Public Utilities [Member] \| II [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Investor Owned And Public Utilities [Member] \| III [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Investor Owned And Public Utilities [Member] \| IV [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Housing Revenue [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	151,000						151,000			157,000
Housing Revenue [Member] \| I/SL [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	143,000						143,000			149,000
Housing Revenue [Member] \| IA [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	3,000						3,000			3,000
Housing Revenue [Member] \| II [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	5,000						5,000			5,000
Housing Revenue [Member] \| III [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Housing Revenue [Member] \| IV [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	$ 0						$ 0			$ 0