Consolidated Balance Sheets - Successor [Member] - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Assets:
Fixed income securities, at fair value (amortized cost of $5,165,245 and $5,435,385)	$ 5,318,195	$ 5,554,215
Fixed income securities pledged as collateral, at fair value (amortized cost of $64,944 and $64,833)	64,928	64,905
Short-term investments, at fair value (amortized cost of $504,093 and $430,827)	504,006	430,788
Other investments	452,032	450,307
Total investments	6,339,161	6,500,215
Cash and cash equivalents	54,238	91,025
Receivable for securities	3,218	2,090
Investment income due and accrued	24,258	26,023
Premium receivables	653,176	661,337
Reinsurance recoverable on paid and unpaid losses	46,466	30,418
Deferred ceded premium	59,471	69,624
Subrogation recoverable	658,875	684,731
Loans	10,125	4,160
Derivative assets	79,047	77,742
Insurance intangible asset	912,173	962,080
Other assets	70,025	158,423
Total assets	23,005,443	22,635,702
Liabilities:
Unearned premiums	893,456	967,258
Loss and loss expense reserves	4,582,153	4,380,769
Ceded premiums payable	39,664	42,529
Obligations under investment agreements	0	82,358
Obligations under investment agreements	(1,866)	(1,720)
Current taxes	26,082	14,280
Long-term debt	988,150	1,114,405
Accrued interest payable	397,974	421,975
Derivative Liability	91,549	319,286
Other liabilities	72,582	76,589
Payable for securities purchased	6,126	1,084
Total liabilities	21,067,230	20,657,678
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	453	452
Additional paid-in capital	197,652	195,267
Accumulated other comprehensive income	38,828	(38,990)
Retained earnings	1,437,641	1,557,681
Treasury stock, shares at cost: 0 and 8,202	(471)	(496)
Total Ambac Financial Group, Inc. stockholders’ equity	1,674,103	1,713,914
Noncontrolling interest	264,110	264,110
Total stockholders’ equity	1,938,213	1,978,024
Total liabilities and stockholders’ equity	23,005,443	22,635,702
Deferred Income Tax Liabilities, Net	1,866	1,720
Variable Interest Entity [Member]
Assets:
Fixed income securities, at fair value (amortized cost of $5,165,245 and $5,435,385)	2,722,316	2,622,566
Restricted cash	5,015	4,873
Loans	11,301,298	10,658,963
Derivative assets	65,507	80,407
Other assets	1,074	1,025
Liabilities:
Long-term debt	11,902,682	11,155,936
Accrued interest payable	860	859
Derivative Liability	2,064,071	2,078,601
Other liabilities	$ 15	$ 29