Segment Information - Schedule of Gross Premiums Written, Net Premiums Earned and Net Change in Fair Value of Credit Derivatives (Detail) (Successor [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Gross Premiums Written	$ 1,062	$ (5,766)
Net premiums earned	65,718	82,547
Net Change In Fair Value Of Credit Derivatives	(2,499)	7,382
Reportable Geographical Components [Member] | United States [Member]
Segment Reporting Information [Line Items]
Gross Premiums Written	(2,366)	(699)
Net premiums earned	52,739	56,758
Net Change In Fair Value Of Credit Derivatives	3,958	6,581
Reportable Geographical Components [Member] | United Kingdom [Member]
Segment Reporting Information [Line Items]
Gross Premiums Written	9,174	(6,166)
Net premiums earned	7,582	20,635
Net Change In Fair Value Of Credit Derivatives	0	0
Reportable Geographical Components [Member] | Other International [Member]
Segment Reporting Information [Line Items]
Gross Premiums Written	(5,746)	1,099
Net premiums earned	5,397	5,154
Net Change In Fair Value Of Credit Derivatives	$ (6,457)	$ 801