Consolidated Statements of Total Comprehensive Income (Successor [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Successor [Member]
Revenues:
Net premiums earned	$ 65,718	$ 82,547
Net investment income:
Securities available-for-sale and short-term	63,332	68,807
Other investments	9,651	1,994
Total net investment income	72,983	70,801
Other-than-temporary impairment losses:
Total other-than-temporary impairment losses	(10,361)	(10,392)
Portion of other-than-temporary impairment recognized in other comprehensive income	7,242	0
Net other-than-temporary impairments	(3,119)	(10,392)
Net realized investment gains	54,101	16,289
Change in fair value of credit derivatives:
Realized gains and other settlements	419	775
Unrealized gains (losses)	(2,918)	6,607
Net change in fair value of credit derivatives	(2,499)	7,382
Derivative products	(37,774)	(53,841)
Net realized losses on extinguishment of debt	(93)	0
Other income (expense)	(788)	1,894
Income (loss) on variable interest entities	6,962	(5,542)
Total revenues	155,491	109,138
Expenses:
Losses and loss (benefit)	(150,952)	(140,011)
Insurance intangible amortization	37,432	31,714
Underwriting and operating expenses	24,523	25,786
Interest expense	27,908	32,328
Total expenses (benefit)	(61,089)	(50,183)
Pre-tax income before reorganization items	216,580	159,321
Reorganization items	0	23
Pre-tax income	216,580	159,298
Provision for income taxes	1,709	3,249
Net income (loss)	214,871	156,049
Less: net (gain) loss attributable to noncontrolling interest	160	107
Net income attributable to common shareholders	214,711	155,942
Other comprehensive income (loss), after tax:
Net income (loss)	214,871	156,049
Unrealized gains (losses) on securities, net of deferred income taxes of $0	(17,448)	88,722
Gains (losses) on foreign currency translation, net of deferred income taxes of $0	(33,805)	4,284
Changes to postretirement benefit, net of tax of $0	(27)	(204)
Total other comprehensive income (loss), net of tax	(51,280)	92,802
Total comprehensive income	163,591	248,851
Less: comprehensive (loss) gain attributable to the noncontrolling interest:
Net (gain) loss	160	107
Currency translation adjustments	(326)	46
Total comprehensive income attributable to Ambac Financial Group, Inc.	$ 163,757	$ 248,698
Net income per share attributable to Ambac Financial Group, Inc. common shareholders:	$ 4.75	$ 3.46
Basic	$ 4.57	$ 3.31