Fair Value Measurements - Summary of Information about Described Model Inputs Used to Determine Fair Value of Each Class of Credit Derivatives (Detail) - Successor [Member] $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) Transactions $ / shares	Dec. 31, 2016 USD ($) Transactions $ / shares
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative, Number of Instruments Held | Transactions	2	8
Other [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Notional outstanding	$ 325,890	$ 737,380
Weighted average reference obligation price | $ / shares	$ 99.3	$ 93.5
Weighted average life (WAL) in years	6 years 6 months	5 years 2 months
Weighted average credit rating	A	A-
Weighted average relative change ratio	23.60%	31.60%
CVA percentage	9.64%	11.14%
Fair value of derivative liabilities	$ 566	$ 15,349