Consolidated Balance Sheets - Successor [Member] - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Assets:
Fixed income securities, available for sale, at fair value (amortized cost: 2016—$5,539,759 and 2015—$4,992,756)	$ 5,650,261	$ 5,043,776
Fixed income securities pledged as collateral, available for sale, at fair value (amortized cost: 2016—$64,667 and 2015—$64,612)	64,918	64,555
Short-term investments, available for sale, at fair value (amortized cost: 2016—$436,759 and 2015—$225,789)	436,760	225,789
Other investments (includes 2016—$294,376 and 2015—$285,261 at fair value)	320,847	310,600
Total investments	6,472,786	5,644,720
Cash and cash equivalents	29,142	35,744
Receivable for securities	10,196	44,030
Investment income due and accrued	25,386	25,264
Premium receivables	782,078	831,575
Reinsurance recoverable on paid and unpaid losses	27,316	43,999
Deferred ceded premium	86,502	96,758
Subrogation recoverable	660,471	1,229,293
Loans	5,109	5,206
Derivative assets	97,559	84,995
Insurance intangible asset	1,149,966	1,212,112
Other assets	221,206	185,877
Total assets	23,718,591	23,728,070
Liabilities:
Unearned premiums	1,192,796	1,280,282
Loss and loss expense reserves	4,303,547	4,088,106
Ceded premiums payable	47,338	53,494
Obligations under investment agreements	100,358	100,358
Deferred Tax Liabilities, Net	1,759	2,205
Current taxes	3,372	5,835
Long-term debt	1,115,284	1,124,950
Accrued interest payable	371,688	355,536
Derivative liabilities	408,331	353,358
Other liabilities	68,693	61,134
Payable for securities purchased	16,760	84,690
Total liabilities	21,706,960	21,769,724
Stockholders’ equity:
Preferred stock, par value $0.01 per share; 20,000,000 shares authorized; issued and outstanding shares—none	0	0
Common stock, par value $0.01 per share; 130,000,000 shares authorized; issued and outstanding shares: 0 and 45,044,222	450	450
Additional paid-in capital	191,895	190,813
Accumulated other comprehensive income	58,012	15,215
Accumulated earnings	1,494,181	1,478,439
Treasury stock, shares at cost: 0 and 8,202	(12)	(118)
Total Ambac Financial Group, Inc. stockholders’ equity	1,744,526	1,684,799
Noncontrolling interest	267,105	273,547
Total stockholders’ equity	2,011,631	1,958,346
Total liabilities and stockholders’ equity	23,718,591	23,728,070
Deferred Income Tax Liabilities, Net	1,759	2,205
Variable Interest Entity [Member]
Assets:
Fixed income securities, available for sale, at fair value (amortized cost: 2016—$5,539,759 and 2015—$4,992,756)	2,622,724	2,588,556
Restricted Cash and Cash Equivalents	5,642	5,822
Investment income due and accrued	3,689	1,213
Loans Receivable, Net	11,516,242	11,690,324
Other assets	2,577	2,582
Liabilities:
Long-term debt	11,998,561	12,327,960
Accrued interest payable	3,474	3,230
Derivative liabilities	2,074,807	1,928,403
Other liabilities	$ 192	$ 183