Financial Guarantee Insurance Contracts - Summary of Balance of RMBS Subrogation Recoveries and Related Claim Liabilities, by Estimation Approach (Detail) - Successor [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Balance Of Rmbs Subrogation Recoveries And Related Claim Liabilities By Estimation Approach [Line Items]
Subrogation recoveries	$ 1,855,073		$ 2,829,575
Random Samples [Member]
Schedule Of Balance Of Rmbs Subrogation Recoveries And Related Claim Liabilities By Estimation Approach [Line Items]
Gross loss reserve before subrogation recoveries	1,298,065		1,850,804
Subrogation recoveries	1,855,073		2,829,575
Gross loss reserve after subrogation recoveries	(557,008)		(978,771)
Random Samples [Member]
Schedule Of Balance Of Rmbs Subrogation Recoveries And Related Claim Liabilities By Estimation Approach [Line Items]
Subrogation recoveries	1,855,073	$ 2,568,353	$ 2,829,575	$ 2,523,540
Impact Of Sponsor Actions In Residential Mortgage Backed Securities Subrogation	(995,000)	0
Other Changes Rmbs Subrogation	$ 20,498	$ 44,813