Segment Information - Schedule of Gross Premiums Written, Net Premiums Earned and Net Change in Fair Value of Credit Derivatives (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 Successor Ambac [Member]	Mar. 31, 2014 Successor Ambac [Member] Reportable Geographical Components [Member] United States [Member]	Mar. 31, 2014 Successor Ambac [Member] Reportable Geographical Components [Member] United Kingdom [Member]	Mar. 31, 2014 Successor Ambac [Member] Reportable Geographical Components [Member] Other International [Member]	Mar. 31, 2013 Predecessor Ambac [Member]	Mar. 31, 2013 Predecessor Ambac [Member] Reportable Geographical Components [Member] United States [Member]	Mar. 31, 2013 Predecessor Ambac [Member] Reportable Geographical Components [Member] United Kingdom [Member]	Mar. 31, 2013 Predecessor Ambac [Member] Reportable Geographical Components [Member] Other International [Member]
Segment Reporting Information [Line Items]
Gross Premiums Written	$ (5,766)	$ (699)	$ (6,166)	$ 1,099	$ (3,530)	$ (8,716)	$ 8,507	$ (3,321)
Net premiums earned	82,547	56,758	20,635	5,154	100,256	81,057	13,754	5,445
Net Change In Fair Value Of Credit Derivatives	$ 7,382	$ 6,581	$ 0	$ 801	$ 12,787	$ 16,530	$ (2,175)	$ (1,568)