Derivative Instruments - Summarize Information by Major Category of CDS Contracts (Detail) - Successor [Member] $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017 USD ($) Transactions	Dec. 31, 2016 USD ($) Transactions
Summary of information by major category of CDS contracts
Number of CDS transactions | Transactions	4	8
Derivative, Average Remaining Maturity	6 years 6 months	5 years 2 months
Gross principal notional outstanding	$ 397,003	$ 737,380
Credit Derivatives [Member]
Summary of information by major category of CDS contracts
Net derivative liabilities at fair value	$ 8,961	$ 15,349