Financial Guarantee Insurance Contracts - Estimated Future Amortization Expense for Insurance Intangible Asset (Detail) - Successor [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Amortization Of Intangible Assets [Line Items]
Amortization of insurance intangible assets	$ 23,242	$ 33,471	$ 51,878	$ 70,996
Intangible Assets, Gross (Excluding Goodwill)	1,568,403		1,568,403		$ 1,581,156
Accumulated amortization on insurance intangible asset	782,195		782,195		734,183
2016	35,309		35,309
2017	66,024		66,024
2018	61,165		61,165
2019	55,771		55,771
2020	51,920		51,920
Thereafter	516,019		516,019
Insurance intangible asset	$ 786,208		$ 786,208		$ 846,973