Financial Guarantee Insurance Contracts - Estimated Future Amortization Expense for Insurance Intangible Asset (Detail) - Successor [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Amortization Of Intangible Assets [Line Items]
Amortization of insurance intangible assets	$ 28,636	$ 37,525
Intangible Assets, Gross (Excluding Goodwill)	1,601,066		$ 1,581,156
Accumulated amortization on insurance intangible asset	768,026		734,183
2016	55,687
2017	68,517
2018	63,475
2019	57,891
2020	53,816
Thereafter	533,654
Insurance intangible asset	$ 833,040		$ 846,973