Financial Guarantee Insurance Contracts - Summary of Loss Reserve Roll-Forward, Net of Subrogation Recoverable and Reinsurance (Detail) € in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2017 EUR (€)	Jun. 30, 2016 USD ($)	Jun. 30, 2016 EUR (€)	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)
Successor [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Beginning gross loss and loss expense reserves	$ 3,696,038		$ 2,858,813
Less reinsurance on loss and loss expense reserves	30,767		44,059
Beginning balance of net loss and loss expense reserves	3,665,271		2,814,754
Current Year Claims and Claims Adjustment Expense	5,137		12
Prior Year Claims and Claims Adjustment Expense	195,974		(157,789)
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	201,111		(157,777)
Claim and loss expense payments, net of subrogation and reinsurance	(153)		0
Claim and loss expense (payments) recoveries, net of subrogation and reinsurance	(7,607)		1,011,956
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid	7,760		(1,011,956)
Liability for Unpaid Claims and Claims Adjustment Expense, Foreign Currency Translation Gain (Loss)	17,622		(48,260)
Liability for Unpaid Claims and Claims Adjustment Expense, Net	3,665,271		2,814,754		$ 3,876,244	$ 3,665,271	$ 3,620,673
Add reinsurance on loss and loss expense reserves	47,034		30,108
Ending gross loss and loss expense reserves	3,923,278		3,650,781
Policyholder Benefits and Claims Incurred, Ceded	16,469		(7,607)
Net Incurred RMBS Subrogation Recoveries	(22,175)		48,646
Ceded Loss And Loss Expenses Paid Not Yet Recovered					$ (568)	$ (349)	$ (1,404)
Euro Member Countries, Euro
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Ending gross loss and loss expense reserves	$ 20,212	€ 17,699	$ 16,655	€ 15,029