Consolidated Statements of Total Comprehensive Income - Successor [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues:
Net premiums earned	$ 197,287	$ 312,595	$ 246,360
Net investment income:
Securities available-for-sale and short-term	281,049	249,337	292,838
Other investments	32,318	16,952	8,108
Total net investment income	313,367	266,289	300,946
Other-than-temporary impairment losses:
Total other-than-temporary impairment losses	(89,700)	(66,692)	(26,632)
Portion of other-than-temporary impairment recognized in other comprehensive income	67,881	41,033	838
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	(21,819)	(25,659)	(25,794)
Net realized investment gains	39,284	53,476	58,777
Change in fair value of credit derivatives:
Realized gains and other settlements	912	2,785	3,043
Unrealized gains (losses)	19,194	38,916	20,863
Net change in fair value of credit derivatives	20,106	41,701	23,906
Derivative products	(50,273)	(42,544)	(181,087)
Net realized gains (losses) on extinguishment of debt	4,845	81	(74,724)
Other income	17,445	7,150	12,498
Income (loss) on variable interest entities	(14,093)	31,569	(32,212)
Total revenues before expenses and reorganization items	506,149	644,658	328,670
Expenses:
Losses and loss expenses (benefit)	(11,489)	(768,707)	(545,574)
Insurance intangible amortization	174,608	169,557	151,830
Operating expenses	113,660	102,702	101,474
Interest expense	124,344	116,537	127,476
Goodwill, Impairment Loss	0	514,511	0
Total expenses (benefit) before reorganization items	401,123	134,600	(164,794)
Pre-tax income before reorganization items	105,026	510,058	493,464
Reorganization items	0	0	211
Pre-tax income	105,026	510,058	493,253
Provision for income taxes	30,709	17,364	9,557
Net income (loss)	74,317	492,694	483,696
Less: net gain (loss) attributable to noncontrolling interest	(526)	(709)	(375)
Net income attributable to common shareholders	74,843	493,403	484,071
Other comprehensive income, after tax:
Net income (loss)	74,317	492,694	483,696
Unrealized gains (losses) on securities, net of deferred income taxes of $0	67,900	(159,730)	252,603
Gains (losses) on foreign currency translation, net of deferred income taxes of $0	(122,128)	(45,025)	(43,599)
Changes to postretirement benefit, net of tax of $0	23	(687)	(816)
Total other comprehensive income (loss), net of tax	(54,205)	(205,442)	208,188
Total comprehensive income	20,112	287,252	691,884
Less: comprehensive (loss) gain attributable to the noncontrolling interest:
Net gain (loss)	(526)	(709)	(375)
Currency translation adjustments	0	(374)	(434)
Total comprehensive income attributable to Ambac Financial Group, Inc.	$ 20,638	$ 288,335	$ 692,693
Basic	$ 1.66	$ 10.92	$ 10.73
Diluted	$ 1.64	$ 10.72	$ 10.31