Consolidated Balance Sheets - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Assets:
Fixed maturity securities, at fair value	$ 2,036,000
Total investments (net of allowance for credit losses of $1 and $0)	2,815,000	$ 2,955,000
Cash and cash equivalents	60,000	17,000
Restricted Cash	7,000	5,000
Premiums Receivable, Net	317,000	323,000
Premium Receivable, Allowance for Credit Loss	8,000	9,000
Reinsurance Recoverable, Allowance for Credit Loss	49	10
Reinsurance Recoverables, Including Reinsurance Premium Paid	48,000	55,000
Deferred ceded premium	100,000	90,000
Subrogation recoverable	1,714,000	2,092,000
Derivative assets	55,000	76,000
Intangible assets	350,000	362,000
Goodwill	46,000	46,000
Other assets	94,000	68,000
Total assets	11,531,000	12,303,000
Liabilities:
Unearned premiums	393,000	395,000
Loss and loss expense reserves	1,067,000	1,570,000
Ceded premiums payable	40,000	33,000
Long-term debt	2,242,000	2,230,000
Accrued interest payable	593,000	576,000
Derivative Liability	76,000	95,000
Other liabilities	135,000	133,000
Total liabilities	10,538,000	11,187,000
Liabilities	10,538,000	11,187,000
Stockholders’ equity:
Preferred stock, par value $0.01 per share; 20,000,000 shares authorized; issued and outstanding shares—none	0	0
Common Stock, Value, Issued	0	0
Additional paid-in capital	262,000	257,000
Accumulated other comprehensive income	(70,000)	58,000
Retained earnings	723,000	726,000
Treasury stock, shares at cost: 0 and 8,202	(2,000)	(3,000)
Total Ambac Financial Group, Inc. stockholders’ equity	914,000	1,038,000
Noncontrolling interest	60,000	60,000
Total stockholders’ equity	974,000	1,098,000
Total liabilities and stockholders’ equity	11,531,000	12,303,000
Available-for-sale Securities, Amortized Cost Basis	2,006,000	2,140,000
Debt Securities, Available-for-sale, Allowance for Credit Loss	1,000	0
Debt Securities, Available-for-sale, Amortized Cost	2,005,000
Xchange
Liabilities:
Redeemable Noncontrolling Interest, Equity, Redemption Value	18,000
Redeemable Noncontrolling Interest, Equity, Carrying Amount		18,000
Short-term Investments [Member]
Assets:
Fixed maturity securities, at fair value	540,000	414,000
Stockholders’ equity:
Available-for-sale Securities, Amortized Cost Basis	540,000	415,000
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Variable Interest Entity, Primary Beneficiary [Member]
Assets:
Fixed maturity securities, at fair value	3,364,000	3,455,000
Restricted Cash	49,000	2,000
Derivative assets	42,000	38,000
Other assets	1,000	2,000
Total assets	5,925,000	6,216,000
Liabilities:
Long-term debt	4,124,000	4,216,000
Derivative Liability	1,866,000	1,940,000
Other liabilities	3,000	0
Total liabilities	5,993,000	6,156,000
Liabilities	5,993,000	6,156,000
Stockholders’ equity:
Financing Receivable, after Allowance for Credit Loss	2,469,000	2,718,000
Gross Investment Income, Operating	(4,000)
Fixed Income Securities [Member]
Assets:
Fixed maturity securities, at fair value	1,383,000	1,730,000
Stockholders’ equity:
Available-for-sale Securities, Amortized Cost Basis	1,352,000	1,605,000
Available-for-sale Securities	1,383,000	1,730,000
Debt Securities, Available-for-sale, Allowance for Credit Loss	1,000	0
Short-term Investments [Member]
Stockholders’ equity:
Available-for-sale Securities	540,000	414,000
Gross Investment Income, Operating	0
Other Investments [Member]
Stockholders’ equity:
Available-for-sale Securities	660,000	690,000
Gross Investment Income, Operating	0
Fixed Income Securities, Trading
Stockholders’ equity:
Available-for-sale Securities, Amortized Cost Basis	119,000	0
Available-for-sale Securities	119,000
Gross Investment Income, Operating	(9,000)
Collateral Pledged [Member] | Fixed Income Securities [Member]
Assets:
Fixed maturity securities, at fair value	114,000	120,000
Stockholders’ equity:
Debt Securities, Available-for-sale, Amortized Cost	15,000	15,000
Collateral Pledged [Member] | Fixed Income Securities [Member] | Short-term Investments [Member]
Assets:
Fixed maturity securities, at fair value	99,000	105,000
Stockholders’ equity:
Available-for-sale Securities, Amortized Cost Basis	99,000	105,000
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Collateral Pledged [Member] | Short-term Investments
Stockholders’ equity:
Available-for-sale Securities, Amortized Cost Basis	99,000	105,000
Collateralized Securities | Fixed Income Securities [Member]
Stockholders’ equity:
Available-for-sale Securities	15,000	15,000
Collateralized Securities | Short-term Investments [Member]
Stockholders’ equity:
Available-for-sale Securities	$ 99,000	$ 105,000