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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-Publisher FASB
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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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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.

+ References

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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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- 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 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.

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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.

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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						6 Months Ended
	Jun. 30, 2022 USD ($)	Jun. 30, 2022 GBP (£)	Jun. 30, 2022 EUR (€)	Jun. 30, 2021 USD ($)	Jun. 30, 2021 GBP (£)	Jun. 30, 2021 EUR (€)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Insurance [Line Items]
Allowance for Doubtful Accounts, Premiums and Other Receivables	$ 6,000			$ 11,000			$ 6,000	$ 11,000	$ 8,000	$ 9,000	$ 13,000	$ 17,000
Financial Guarantee Insurance Contracts, Accelerated Premium Revenue, Amount	2,344			91			6,267	1,039
Past Due Premiums Receivable	41						41			49
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Beginning premium receivable							320,000	370,000
Premium receipts							22,000	19,000
Adjustments for changes in expected and contractual cash flows							(5,000)	(17,000)
Accretion of premium receivable discount							4,000	4,000
Uncollectable premiums							3,000	6,000
Other adjustments (including foreign exchange)							(12,000)	0
Ending premium receivable	288,000			344,000			288,000	344,000
Premium Receivable, Allowance for Credit Loss	6,000						6,000			9,000
Premium Receivable, Credit Loss Expense (Reversal)	(1,000)			(1,000)			(2,000)	(5,000)
Premium Receivable, Allowance for Credit Loss, Writeoff	(1,000)			(1,000)			(1,000)	(1,000)
Premium Receivable, Allowance for Credit Loss, Recovery	0			0			0	0
Financing Receivable, 90 Days or More Past Due, Still Accruing	26						26			34
Premiums Receivable, Gross	295,000						295,000			329,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	846,000			1,123,000			846,000	1,123,000	$ 974,000	1,098,000	$ 1,123,000	$ 1,140,000
Premiums Receivable, Net	311,000						311,000			323,000
Specialty Property & Casualty Program
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	22,000						22,000			2,000
Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	155,000						155,000			159,000
Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	34,000						34,000			45,000
International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	106,000						106,000			125,000
I/SL [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	250,000						250,000			277,000
I/SL [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	147,000						147,000			151,000
I/SL [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	14,000						14,000			19,000
I/SL [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	89,000						89,000			107,000
IA [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	11,000						11,000			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	7,000						7,000			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	17,000						17,000			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	12,000						12,000			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	12,000						12,000			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	91,000	£ 74		122,000	£ 88		91,000	122,000
Euro Member Countries, Euro
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Ending premium receivable	15,000		€ 14	$ 16,000		€ 13	15,000	$ 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	5,000						5,000			5,000
Other International [Member] \| I/SL [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	5,000						5,000			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	13,000						13,000			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	12,000						12,000			12,000
Structured Insurance [Domain] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	7,000						7,000			10,000
Structured Insurance [Domain] \| I/SL [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	7,000						7,000			10,000
Structured Insurance [Domain] \| IA [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Structured Insurance [Domain] \| II [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Structured Insurance [Domain] \| III [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Structured Insurance [Domain] \| IV [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	0						0			0
Student Loans [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	10,000						10,000			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	8,000						8,000			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	5,000						5,000			7,000
Other Structured Finance [Member] \| I/SL [Member] \| Structured Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	5,000						5,000			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	83,000						83,000			93,000
Sovereign And Sub Sovereign [Member] \| I/SL [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	67,000						67,000			74,000
Sovereign And Sub Sovereign [Member] \| IA [Member] \| International Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	7,000						7,000			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	18,000						18,000			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	18,000						18,000			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	153,000						153,000			157,000
Housing Revenue [Member] \| I/SL [Member] \| Public Finance [Member]
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward]
Premiums Receivable, Gross	145,000						145,000			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