Financial Guarantee Insurance Contracts - Additional Information (Detail) - USD ($)	3 Months Ended								4 Months Ended	8 Months Ended	12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Apr. 30, 2013	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Insurance [Line Items]
Amount Of Insured Par Outstanding Ceded To Reinsurer	$ 9,711,000,000										$ 9,711,000,000
Ceded Principal Outstanding Major Reinsurer Percentage											8.10%
Deferred Ceded Premiums And Reinsurance Recoverables	140,757,000										$ 140,757,000
Accrued rate of interest on outstanding policy obligations (percent)											5.10%	5.10%
Weighted average period of future premiums											9 years 2 months 12 days	10 years 1 month 6 days
Losses and loss expense reserves ceded to reinsurers	44,059,000				$ 100,355,000						$ 44,059,000	$ 100,355,000
Subrogation recoveries	2,829,575,000				2,523,540,000						2,829,575,000	2,523,540,000
Subrogation recoveries, net of reinsurance	2,800,149,000				2,496,515,000						2,800,149,000	2,496,515,000
Letters of Credit Outstanding, Amount	136,167,000										136,167,000
Financial Guarantee Outstanding Principal Ceded To Third Parties	10,936,000,000										10,936,000,000
Successor [Member]
Insurance [Line Items]
Financial Guarantee Gross Outstanding Principal Assumed From Third Parties	243,600,000				245,900,000						243,600,000	245,900,000
Reinsurance Payable	53,494,000				60,436,000				$ 92,468,000		$ 53,494,000	$ 60,436,000
Transactions with non-investment grade internal ratings											27.00%	32.00%
Non-investment grade RMBS on total premiums receivable											8.00%	7.00%
Percentage of student loan transactions on total premium receivables											5.00%	8.00%
Percentage related to asset-backed transaction											5.00%	6.00%
Uncollectable premium receivables	15,240,000				17,780,000						$ 15,240,000	$ 17,780,000
Past due premiums on policies insuring non-investment grade obligations amount	500										500
Accelerated premium revenue for retired obligations										$ 56,541,000	137,400,000	29,964,000
Reinsurance recoveries of losses included in losses and loss expenses										14,106,000	47,085,000	21,164,000
Losses and loss expense reserves ceded to reinsurers	44,059,000				100,355,000				138,155,000	122,357,000	44,059,000	100,355,000	$ 122,357,000
Intangible amortization expense	54,357,000	$ 39,680,000	$ 38,088,000	$ 37,432,000	41,952,000	$ 41,908,000	$ 36,256,000	$ 31,714,000		$ 99,658,000	169,557,000	151,830,000
Insurance intangible asset	1,212,112,000				1,410,920,000				1,658,972,000		1,212,112,000	1,410,920,000
Accumulated amortization on insurance intangible asset	$ 414,454,000				$ 249,205,000						414,454,000	249,205,000
Successor [Member] | Insurance Intangible Asset [Member]
Insurance [Line Items]
Intangible amortization expense											$ 169,557,000	$ 151,830,000	$ 99,658,000
Predecessor [Member]
Insurance [Line Items]
Reinsurance Payable									92,468,000
Accelerated premium revenue for retired obligations									36,433,000
Reinsurance recoveries of losses included in losses and loss expenses									(3,889,000)
Losses and loss expense reserves ceded to reinsurers									138,155,000					$ 147,409,000
Intangible amortization expense									0
Insurance intangible asset									$ 0
Loss Reserves [Member] | Successor [Member]
Insurance [Line Items]
Weighted average risk-free rate used to discount loss reserves											2.40%	2.30%