Consolidated Statements of Total Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		5 Months Ended	9 Months Ended	4 Months Ended
	Sep. 30, 2014 Successor Ambac [Member]	Sep. 30, 2013 Successor Ambac [Member]	Sep. 30, 2013 Successor Ambac [Member]	Sep. 30, 2014 Successor Ambac [Member]	Apr. 30, 2013 Predecessor Ambac [Member]
Revenues:
Net premiums earned	$ 64,831	$ 70,949	$ 128,988	$ 212,391	$ 130,000
Net investment income:
Securities available-for-sale and short-term	82,881	51,776	80,987	228,570	116,371
Other investments	700	350	(2,665)	5,905	369
Total net investment income	83,581	52,126	78,322	234,475	116,740
Other-than-temporary impairment losses:
Total other-than-temporary impairment losses	(6,997)	(38,553)	(40,557)	(26,440)	(467)
Portion of loss recognized in other comprehensive income	1,986	516	518	2,283	0
Net other-than-temporary impairment losses recognized in earnings	(5,011)	(38,037)	(40,039)	(24,157)	(467)
Net realized investment gains (losses)	10,045	(10,310)	8,162	29,401	53,305
Change in fair value of credit derivatives:
Realized gains (losses) and other settlements	596	1,580	7,654	2,088	3,444
Unrealized gains (losses)	6,820	29,614	74,760	11,491	(63,828)
Net change in fair value of credit derivatives	7,416	31,194	82,414	13,579	(60,384)
Derivative products	(15,685)	12,372	96,085	(117,511)	(33,735)
Other Income Loss	1,046	(1,751)	428	8,206	8,363
Income (loss) on variable interest entities	9,116	55,109	59,707	(34,574)	426,566
Total revenues before expenses and reorganization items	155,339	171,652	414,067	321,810	640,388
Losses and loss expenses (benefit)
Losses and loss expenses (benefit)	(28,698)	(154,290)	(180,407)	6,608	(38,056)
Insurance intangible amortization	41,908	37,473	62,425	109,878	0
Underwriting and operating expenses	25,513	25,047	41,264	75,332	44,566
Interest expense	31,841	31,817	52,961	96,122	31,025
Total expenses before reorganization items	70,564	(59,953)	(23,757)	287,940	37,535
Pre-tax (loss) income from continuing operations before reorganization items	84,775	231,605	437,824	33,870	602,853
Reorganization items	2	4	428	211	(2,745,180)
Pre-tax (loss) income from continuing operations	84,773	231,601	437,396	33,659	3,348,033
Provision (benefit) for income taxes	2,344	594	1,107	3,414	755
Net (loss) income	82,429	231,007	436,289	30,245	3,347,278
Less: net (loss) gain attributable to noncontrolling interest	(21)	32	(367)	(242)	(1,771)
Net (loss) income attributable to common shareholders	82,450	230,975	436,656	30,487	3,349,049
Net (loss) income
Net (loss) income	82,429	231,007	436,289	30,245	3,347,278
Unrealized fain (loss) on securities, net of deferred income taxes of $0	(17,225)	53,877	(37,106)	256,660	175,347
Gain (loss) on foreign currency translation, net of deferred income taxes of $0	(38,429)	39,798	27,136	(17,001)	(428)
Changes to postretirement benefit, net of tax of $0	(204)	0	0	(612)	185
Total other comprehensive (loss) income, net of tax	(55,858)	93,675	(9,970)	239,047	175,104
Total comprehensive income (loss)	26,571	324,682	426,319	269,292	3,522,382
Net (loss) gain
Noncontrolling interest in subsidiaries’ earnings	(21)	32	(367)	(242)	(1,771)
Total comprehensive income (loss) attributable to Ambac Financial Group, Inc.	(395)	414	276	(157)	229
Total comprehensive income (loss) attributable to Ambac Financial Group, Inc.	$ 26,987	$ 324,236	$ 426,410	$ 269,691	$ 3,523,924
Net income (loss) per share attributable to Ambac Financial Group, Inc. common shareholders (in dollars per share)	$ 1.83	$ 5.13	$ 9.70	$ 0.68	$ 11.07
Net income (loss) per diluted share attributable to Ambac Financial Group, Inc. common shareholders (in dollars per share)	$ 1.77	$ 4.98	$ 9.40	$ 0.65	$ 11.07