Financial Guarantee Insurance Contracts - Summary of Balance of RMBS Subrogation Recoveries and Related Claim Liabilities, by Estimation Approach (Detail) - Successor [Member] - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Balance Of Rmbs Subrogation Recoveries And Related Claim Liabilities By Estimation Approach [Line Items]
Balance Of Gross Rmbs Subrogation Recoveries	$ 2,556,574		$ 2,523,540
Balance Of Rmbs Subrogation Recoveries Net Of Reinsurance	2,529,300		2,496,515
Subrogation recoveries	2,556,574	$ 2,284,424	2,523,540	$ 2,206,598
Additional Transactions Reviewed Changes in RMBS Subrogation		24,510
Changes in Estimation Approach In Rmbs Subrogation		123,236
Impact Of Sponsor Actions In Residential Mortgage Backed Securities Subrogation	0	(90,000)
Other Changes Rmbs Subrogation	33,034	20,080
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	1,869,797		1,897,426
Subrogation recoveries	2,556,574		2,523,540
Gross loss reserve after subrogation recoveries	(686,777)		(626,114)
Adverse Samples [Member]
Schedule Of Balance Of Rmbs Subrogation Recoveries And Related Claim Liabilities By Estimation Approach [Line Items]
Subrogation recoveries	0	0	0	1,252,773
Additional Transactions Reviewed Changes in RMBS Subrogation		0
Changes in Estimation Approach In Rmbs Subrogation		(1,218,681)
Impact Of Sponsor Actions In Residential Mortgage Backed Securities Subrogation	0	0
Other Changes Rmbs Subrogation	0	(34,092)
Random Samples [Member]
Schedule Of Balance Of Rmbs Subrogation Recoveries And Related Claim Liabilities By Estimation Approach [Line Items]
Subrogation recoveries	2,556,574	2,284,424	$ 2,523,540	$ 953,825
Additional Transactions Reviewed Changes in RMBS Subrogation		24,510
Changes in Estimation Approach In Rmbs Subrogation		1,341,917
Impact Of Sponsor Actions In Residential Mortgage Backed Securities Subrogation	0	(90,000)
Other Changes Rmbs Subrogation	$ 33,034	$ 54,172