Financial Guarantee Insurance Contracts - Summary of Rollforward of RMBS Subrogation, by Estimation Approach (Detail) - Successor [Member] - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Subrogation By Estimation Approach [Roll Forward]
Discounted RMBS subrogation (gross of reinsurance), beginning balance	$ 2,829,575
Changes recognized
Discounted RMBS subrogation (gross of reinsurance), ending balance	1,923,256
Random Samples [Member]
Subrogation By Estimation Approach [Roll Forward]
Discounted RMBS subrogation (gross of reinsurance), beginning balance	2,829,575	$ 2,523,540
Changes recognized
Impact of sponsor actions	(995,000)	0
Other Changes Rmbs Subrogation	88,681	31,921
Discounted RMBS subrogation (gross of reinsurance), ending balance	$ 1,923,256	$ 2,555,461