Financial Guarantee Insurance Contracts - Additional Information (Detail) (USD $)	12 Months Ended		2 Months Ended	3 Months Ended						8 Months Ended	1 Months Ended	3 Months Ended	4 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2013	Apr. 30, 2013	Mar. 31, 2013	Apr. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
Insurance [Line Items]
Amount Of Insured Par Outstanding Ceded To Reinsurer	$ 13,365,743,000			$ 13,365,743,000
Ceded Principal Outstanding Major Reinsurer Percentage	8.40%
Deferred Ceded Premiums And Reinsurance Recoverables	223,114,000			223,114,000
Accrued rate of interest on outstanding policy obligations (percent)	5.10%
Weighted average period of future premiums	10 years 1 month 6 days	9 years 7 months 6 days
Transactions with non-investment grade internal ratings	32.00%	44.00%
Non-investment grade RMBS on total premiums receivable	7.00%	7.00%
Percentage of student loan transactions on total premium receivables	8.00%	7.00%
Percentage related to asset-backed transaction	0.00%	17.00%
Uncollectable premium receivables	17,780,000	15,262,000		17,780,000				15,262,000		15,262,000
Past due premiums on policies insuring non-investment grade obligations amount	500
Losses and loss expense reserves ceded to reinsurers	100,355,000	122,357,000		100,355,000				122,357,000		122,357,000
Subrogation recoveries	2,523,540,000	2,206,598,000		2,523,540,000				2,206,598,000		2,206,598,000
Subrogation recoveries, net of reinsurance	2,496,515,000	2,183,652,000		2,496,515,000				2,183,652,000		2,183,652,000
Accumulated amortization on insurance intangible asset	249,205,000	100,767,000		249,205,000				100,767,000		100,767,000
Letters of Credit Outstanding, Amount	141,337,000			141,337,000
Financial Guarantee Outstanding Principal Ceded To Third Parties	14,954,444,000			14,954,444,000
Successor [Member]
Insurance [Line Items]
Financial Guarantee Gross Outstanding Principal Assumed From Third Parties	245,900,000	248,225,000		245,900,000				248,225,000		248,225,000
Reinsurance Payable	60,436,000	70,962,000		60,436,000				70,962,000		70,962,000	92,468,000		92,468,000
Accelerated premium revenue for retired obligations	29,964,000									56,541,000
Reinsurance recoveries of losses included in losses and loss expenses	21,164,000									14,106,000
Losses and loss expense reserves ceded to reinsurers	100,355,000	122,357,000		100,355,000				122,357,000		122,357,000	138,155,000		138,155,000
Intangible amortization expense	151,830,000		24,952,000	41,952,000	41,908,000	36,256,000	31,714,000	37,233,000	37,473,000	99,658,000
Insurance intangible asset	1,410,920,000	1,597,965,000		1,410,920,000				1,597,965,000		1,597,965,000	1,658,972,000		1,658,972,000
Successor [Member] | Insurance Intangible Asset [Member]
Insurance [Line Items]
Intangible amortization expense	151,830,000									99,658,000
Predecessor [Member]
Insurance [Line Items]
Reinsurance Payable											92,468,000		92,468,000
Accelerated premium revenue for retired obligations													36,433,000	127,628,000
Reinsurance recoveries of losses included in losses and loss expenses													(3,889,000)	(6,996,000)
Losses and loss expense reserves ceded to reinsurers											138,155,000		138,155,000	147,409,000	153,480,000
Intangible amortization expense											0	0	0	0
Insurance intangible asset											$ 0		$ 0
Loss Reserves [Member]
Insurance [Line Items]
Weighted average risk-free rate used to discount loss reserves	2.30%	3.20%