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	2 Months Ended	3 Months Ended						8 Months Ended	12 Months Ended	1 Months Ended	3 Months Ended	4 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2014	Apr. 30, 2013	Mar. 31, 2013	Apr. 30, 2013	Dec. 31, 2012
Successor [Member]
Segment Reporting Information [Line Items]
Gross Premiums Written	$ (34,081)	$ (223,358)	$ (13,700)	$ (45,486)	$ (5,766)	$ (11,848)	$ (34,380)	$ (80,309)	$ (288,310)
Net premiums earned	58,039	33,969	64,831	65,013	82,547	84,530	70,949	213,518	246,360
Net Change In Fair Value Of Credit Derivatives	51,220	10,327	7,416	(1,219)	7,382	110,455	31,194	192,869	23,906
Successor [Member] | Reportable Geographical Components [Member] | United States [Member]
Segment Reporting Information [Line Items]
Gross Premiums Written								(61,255)	(46,279)
Net premiums earned								165,099	197,154
Net Change In Fair Value Of Credit Derivatives								122,696	8,669
Successor [Member] | Reportable Geographical Components [Member] | United Kingdom [Member]
Segment Reporting Information [Line Items]
Gross Premiums Written								(7,368)	(221,516)
Net premiums earned								35,387	31,672
Net Change In Fair Value Of Credit Derivatives								22,548	0
Successor [Member] | Reportable Geographical Components [Member] | Other International [Member]
Segment Reporting Information [Line Items]
Gross Premiums Written								(11,686)	(20,515)
Net premiums earned								13,032	17,534
Net Change In Fair Value Of Credit Derivatives								47,625	15,237
Predecessor [Member]
Segment Reporting Information [Line Items]
Gross Premiums Written										(10,595)	(3,530)	(14,125)	(277,508)
Net premiums earned										29,744	100,256	130,000	414,604
Net Change In Fair Value Of Credit Derivatives										(73,171)	12,787	(60,384)	(9,219)
Predecessor [Member] | Reportable Geographical Components [Member] | United States [Member]
Segment Reporting Information [Line Items]
Gross Premiums Written												(16,102)	(260,517)
Net premiums earned												104,594	315,367
Net Change In Fair Value Of Credit Derivatives												(31,134)	(8,496)
Predecessor [Member] | Reportable Geographical Components [Member] | United Kingdom [Member]
Segment Reporting Information [Line Items]
Gross Premiums Written												10,673	10,785
Net premiums earned												18,071	73,955
Net Change In Fair Value Of Credit Derivatives												(5,861)	(5,709)
Predecessor [Member] | Reportable Geographical Components [Member] | Other International [Member]
Segment Reporting Information [Line Items]
Gross Premiums Written												(8,696)	(27,776)
Net premiums earned												7,335	25,282
Net Change In Fair Value Of Credit Derivatives												$ (23,389)	$ 4,986