Consolidated Balance Sheets - Successor [Member] - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Assets:
Fixed income securities, available for sale, at fair value (amortized cost: $5,550,887 and $4,992,756)	$ 5,709,464	$ 5,043,776
Fixed income securities pledged as collateral, available for sale, at fair value (amortized cost: $64,721 and $64,612)	65,068	64,555
Short-term investments, available for sale, at fair value (amortized cost: $336,222 and $225,789)	336,222	225,789
Other investments (includes $383,107 and $285,261 at fair value)	410,727	310,600
Total investments	6,521,481	5,644,720
Cash and cash equivalents	23,044	35,744
Receivable for securities	2,400	44,030
Investment income due and accrued	25,082	25,264
Premium receivables	741,414	831,575
Reinsurance recoverable on paid and unpaid losses	28,704	43,999
Deferred ceded premium	82,055	96,758
Subrogation recoverable	677,157	1,229,293
Loans	4,615	5,206
Derivative assets	104,353	84,995
Insurance intangible asset	1,075,605	1,212,112
Other assets	252,163	185,877
Total assets	23,199,111	23,728,070
Liabilities:
Unearned premiums	1,122,946	1,280,282
Loss and loss expense reserves	4,327,938	4,088,106
Ceded premiums payable	45,727	53,494
Obligations under investment agreements	82,358	100,358
Deferred taxes	1,712	2,205
Current taxes	4,858	5,835
Long-term debt	1,112,920	1,124,950
Accrued interest payable	380,117	355,536
Derivative liabilities	437,163	353,358
Other liabilities	59,040	61,134
Payable for securities purchased	54,696	84,690
Total liabilities	21,136,274	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: 45,121,788 and 45,044,222	451	450
Additional paid-in capital	193,074	190,813
Accumulated other comprehensive income	50,775	15,215
Retained earnings	1,551,724	1,478,439
Treasury stock, shares at cost: 0 and 8,202	0	(118)
Total Ambac Financial Group, Inc. stockholders’ equity	1,796,024	1,684,799
Noncontrolling interest	266,813	273,547
Total stockholders’ equity	2,062,837	1,958,346
Total liabilities and stockholders’ equity	23,199,111	23,728,070
Deferred Income Tax Liabilities, Net	1,712	2,205
Variable Interest Entity [Member]
Assets:
Fixed income securities, available for sale, at fair value (amortized cost: $5,550,887 and $4,992,756)	2,577,293	2,588,556
Restricted cash	5,461	5,822
Investment income due and accrued	1,167	1,213
Loans	11,074,772	11,690,324
Other assets	2,345	2,582
Liabilities:
Long-term debt	11,444,892	12,327,960
Accrued interest payable	870	3,230
Derivative liabilities	2,060,878	1,928,403
Other liabilities	$ 159	$ 183