The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

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Segment Information - Summary of Financial Information by Reportable Segment (Detail) (USD $) In Thousands, unless otherwise specified		8 Months Ended		8 Months Ended					4 Months Ended	12 Months Ended	4 Months Ended	12 Months Ended		4 Months Ended	12 Months Ended	4 Months Ended	12 Months Ended	4 Months Ended	12 Months Ended	8 Months Ended						4 Months Ended	12 Months Ended	4 Months Ended	12 Months Ended	4 Months Ended	12 Months Ended	4 Months Ended	12 Months Ended	4 Months Ended	12 Months Ended	4 Months Ended	12 Months Ended	8 Months Ended			4 Months Ended	12 Months Ended		4 Months Ended	12 Months Ended
	Apr. 30, 2013	Dec. 31, 2013 Successor Ambac [Member]	Apr. 30, 2013 Successor Ambac [Member]	Dec. 31, 2013 Successor Ambac [Member] Unaffiliated Customers [Member]	Dec. 31, 2013 Successor Ambac [Member] Inter-Segment [Member]	Dec. 31, 2013 Successor Ambac [Member] Corporate and Other [Member]	Dec. 31, 2013 Successor Ambac [Member] Corporate and Other [Member] Unaffiliated Customers [Member]	Dec. 31, 2013 Successor Ambac [Member] Corporate and Other [Member] Inter-Segment [Member]	Apr. 30, 2013 Predecessor Ambac [Member]	Dec. 31, 2012 Predecessor Ambac [Member]	Apr. 30, 2013 Predecessor Ambac [Member] Unaffiliated Customers [Member]	Dec. 31, 2012 Predecessor Ambac [Member] Unaffiliated Customers [Member]	Dec. 31, 2012 Predecessor Ambac [Member] Inter-Segment [Member]	Apr. 30, 2013 Predecessor Ambac [Member] Corporate and Other [Member]	Dec. 31, 2012 Predecessor Ambac [Member] Corporate and Other [Member]	Apr. 30, 2013 Predecessor Ambac [Member] Corporate and Other [Member] Unaffiliated Customers [Member]	Dec. 31, 2012 Predecessor Ambac [Member] Corporate and Other [Member] Unaffiliated Customers [Member]	Apr. 30, 2013 Predecessor Ambac [Member] Corporate and Other [Member] Inter-Segment [Member]	Dec. 31, 2012 Predecessor Ambac [Member] Corporate and Other [Member] Inter-Segment [Member]	Dec. 31, 2013 Operating Segments [Member] Successor Ambac [Member] Financial Guarantee [Member]	Dec. 31, 2013 Operating Segments [Member] Successor Ambac [Member] Financial Guarantee [Member] Unaffiliated Customers [Member]	Dec. 31, 2013 Operating Segments [Member] Successor Ambac [Member] Financial Guarantee [Member] Inter-Segment [Member]	Dec. 31, 2013 Operating Segments [Member] Successor Ambac [Member] Financial Services [Member]	Dec. 31, 2013 Operating Segments [Member] Successor Ambac [Member] Financial Services [Member] Unaffiliated Customers [Member]	Dec. 31, 2013 Operating Segments [Member] Successor Ambac [Member] Financial Services [Member] Inter-Segment [Member]	Apr. 30, 2013 Operating Segments [Member] Predecessor Ambac [Member] Financial Guarantee [Member]	Dec. 31, 2012 Operating Segments [Member] Predecessor Ambac [Member] Financial Guarantee [Member]	Apr. 30, 2013 Operating Segments [Member] Predecessor Ambac [Member] Financial Guarantee [Member] Unaffiliated Customers [Member]	Dec. 31, 2012 Operating Segments [Member] Predecessor Ambac [Member] Financial Guarantee [Member] Unaffiliated Customers [Member]	Apr. 30, 2013 Operating Segments [Member] Predecessor Ambac [Member] Financial Guarantee [Member] Inter-Segment [Member]	Dec. 31, 2012 Operating Segments [Member] Predecessor Ambac [Member] Financial Guarantee [Member] Inter-Segment [Member]	Apr. 30, 2013 Operating Segments [Member] Predecessor Ambac [Member] Financial Services [Member]	Dec. 31, 2012 Operating Segments [Member] Predecessor Ambac [Member] Financial Services [Member]	Apr. 30, 2013 Operating Segments [Member] Predecessor Ambac [Member] Financial Services [Member] Unaffiliated Customers [Member]	Dec. 31, 2012 Operating Segments [Member] Predecessor Ambac [Member] Financial Services [Member] Unaffiliated Customers [Member]	Apr. 30, 2013 Operating Segments [Member] Predecessor Ambac [Member] Financial Services [Member] Inter-Segment [Member]	Dec. 31, 2012 Operating Segments [Member] Predecessor Ambac [Member] Financial Services [Member] Inter-Segment [Member]	Dec. 31, 2013 Inter-segment Eliminations [Member] Successor Ambac [Member]	Dec. 31, 2013 Inter-segment Eliminations [Member] Successor Ambac [Member] Unaffiliated Customers [Member]	Dec. 31, 2013 Inter-segment Eliminations [Member] Successor Ambac [Member] Inter-Segment [Member]	Apr. 30, 2013 Inter-segment Eliminations [Member] Predecessor Ambac [Member]	Dec. 31, 2012 Inter-segment Eliminations [Member] Predecessor Ambac [Member]	Dec. 31, 2012 Inter-segment Eliminations [Member] Predecessor Ambac [Member] Unaffiliated Customers [Member]	Apr. 30, 2013 Inter-segment Eliminations [Member] Predecessor Ambac [Member] Inter-Segment [Member]	Dec. 31, 2012 Inter-segment Eliminations [Member] Predecessor Ambac [Member] Inter-Segment [Member]
Revenues:
Total revenues before expenses and reorganization items		$ 581,048		$ 581,048		$ 22,296	$ 170	$ 22,126	$ 640,388	$ 685,689	$ 640,388	$ 685,689		$ 197,094	$ 980	$ 39	$ 335	$ 197,055	$ 645	$ 466,538	$ 464,701	$ 1,837	$ 114,967	$ 116,177	$ (1,210)	$ 633,950	$ 763,520	$ 633,010	$ 758,331	$ 940	$ 5,189	$ 6,457	$ (77,969)	$ 7,339	$ (72,977)	$ (882)	$ (4,992)	$ (22,753)		$ (22,753)	$ (197,113)	$ (842)		$ (197,113)	$ (842)
Pre-tax income (loss) from continuing operations:
Pre-tax income (loss) from continuing operations		512,316		512,316		21,453	(3,354)	24,807	3,348,033	(256,505)	3,348,033	(256,505)		1,712,923	(1,534)	1,514,635	(6,729)	198,288	5,195	379,488	402,651	(23,163)	111,375	113,019	(1,644)	1,632,978	(166,181)	1,830,165	(166,761)	(197,187)	580	2,132	(88,790)	3,233	(83,015)	(1,101)	(5,775)
Total assets	28,853,435	27,106,939	28,853,435			36,956			26,969,994	27,085,265				29,403	32,257					26,597,097			472,886			28,287,321	26,519,480					536,711	533,528
Net investment income		146,446				62			116,740	382,902				39	221					145,269			1,115			115,129	365,912					1,572	16,769
Insurance intangible amortization		99,658																		99,658
Interest expense		84,950							31,025	112,320										83,595			1,355			29,718	105,973					1,307	6,347
Reorganization items		$ 493				$ 493			$ (2,745,180)	$ 7,215				$ (1,515,135)	$ 7,215											$ (1,231,550)						$ 1,505