Consolidated Statements of Total Comprehensive Income - Successor [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues:
Net premiums earned	$ 60,879	$ 65,013	$ 126,597	$ 147,560
Net investment income:
Securities available-for-sale and short-term	62,278	76,882	125,610	145,689
Other investments	2,475	3,211	12,126	5,205
Total net investment income	64,753	80,093	137,736	150,894
Other-than-temporary impairment losses:
Total other-than-temporary impairment losses	(1,391)	(7,392)	(11,752)	(15,022)
Portion of other-than-temporary impairment recognized in other comprehensive income	371	(1,362)	7,613	(4,124)
Net other-than-temporary impairments	(1,020)	(8,754)	(4,139)	(19,146)
Net realized investment (losses) gains	(5,353)	3,067	48,748	19,356
Change in fair value of credit derivatives:
Realized gains and other settlements	407	717	826	1,492
Unrealized gains (losses)	9,886	(1,936)	6,968	4,671
Net change in fair value of credit derivatives	10,293	(1,219)	7,794	6,163
Derivative products	50,999	(47,985)	13,225	(101,826)
Net realized losses on extinguishment of debt	(1,246)	0	(1,339)	0
Other income (expense)	(1,156)	5,266	(1,944)	7,160
Income (loss) on variable interest entities	52,603	(38,148)	59,565	(43,690)
Total revenues	230,752	57,333	386,243	166,471
Expenses:
Losses and loss expense (benefit)	(147,477)	175,317	(298,429)	35,306
Insurance intangible amortization	38,088	36,256	75,520	67,970
Underwriting and operating expenses	25,873	24,033	50,396	49,819
Interest expense	28,173	31,953	56,081	64,281
Total expenses (benefit)	(55,343)	267,559	(116,432)	217,376
Pre-tax income (loss) before reorganization items	286,095	(210,226)	502,675	(50,905)
Reorganization items	0	186	0	209
Pre-tax income (loss)	286,095	(210,412)	502,675	(51,114)
Provision (benefit) for income taxes	3,917	(2,179)	5,626	1,070
Net income (loss)	282,178	(208,233)	497,049	(52,184)
Less: net (gain) loss attributable to noncontrolling interest	(517)	(328)	(357)	(221)
Net income (loss) attributable to common shareholders	282,695	(207,905)	497,406	(51,963)
Other comprehensive income (loss), after tax:
Net income (loss)	282,178	(208,233)	497,049	(52,184)
Unrealized gains (losses) on securities, net of deferred income taxes of $0	(113,839)	185,163	(131,287)	273,885
Gains (losses) on foreign currency translation, net of deferred income taxes of $0	40,490	17,144	6,685	21,428
Changes to postretirement benefit, net of tax of $0	(220)	(204)	(247)	(408)
Total other comprehensive income (loss), net of tax	(73,569)	202,103	(124,849)	294,905
Total comprehensive income (loss)	208,609	(6,130)	372,200	242,721
Less: comprehensive (loss) gain attributable to the noncontrolling interest:
Net (gain) loss	(517)	(328)	(357)	(221)
Currency translation adjustments	398	192	72	238
Total comprehensive income attributable to Ambac Financial Group, Inc.	$ 208,728	$ (5,994)	$ 372,485	$ 242,704
Net income (loss) per share attributable to Ambac Financial Group, Inc. common shareholders
Basic	$ 6.26	$ (4.61)	$ 11.01	$ (1.15)
Diluted	$ 6.05	$ (4.61)	$ 10.62	$ (1.15)