Financial Guarantee Insurance Contracts - Summary of Rollforward of RMBS Subrogation, by Estimation Approach (Detail) - Successor [Member] - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Subrogation By Estimation Approach [Roll Forward]
Discounted RMBS subrogation (gross of reinsurance), beginning balance	$ 2,523,540	$ 2,206,598
Changes recognized
Additional Transactions Reviewed Changes in RMBS Subrogation		24,510
Changes in Estimation Approach In Rmbs Subrogation		123,236
Impact of sponsor actions	0	(90,000)
Other Changes Rmbs Subrogation	33,034	20,080
Discounted RMBS subrogation (gross of reinsurance), ending balance	2,556,574	2,284,424
Random Samples [Member]
Subrogation By Estimation Approach [Roll Forward]
Discounted RMBS subrogation (gross of reinsurance), beginning balance	2,523,540	953,825
Changes recognized
Additional Transactions Reviewed Changes in RMBS Subrogation		24,510
Changes in Estimation Approach In Rmbs Subrogation		1,341,917
Impact of sponsor actions	0	(90,000)
Other Changes Rmbs Subrogation	33,034	54,172
Discounted RMBS subrogation (gross of reinsurance), ending balance	2,556,574	2,284,424
Adverse Samples [Member]
Subrogation By Estimation Approach [Roll Forward]
Discounted RMBS subrogation (gross of reinsurance), beginning balance	0	1,252,773
Changes recognized
Additional Transactions Reviewed Changes in RMBS Subrogation		0
Changes in Estimation Approach In Rmbs Subrogation		(1,218,681)
Impact of sponsor actions	0	0
Other Changes Rmbs Subrogation	0	(34,092)
Discounted RMBS subrogation (gross of reinsurance), ending balance	$ 0	$ 0