Summary of Significant Accounting Policies - Common Stock and Convertible Stock Dilutive in Computation of Earning Per Share (Detail) shares in Thousands, EquityUnit in Thousands	3 Months Ended
Mar. 31, 2019 EquityUnit $ / EquityUnit	Mar. 31, 2018 EquityUnit $ / shares $ / EquityUnit shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average PSUs \| EquityUnit	335
Weighted average grant date fair value per unit \| $ / EquityUnit	12.93
Predecessor
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average PSUs \| EquityUnit		418
Weighted average grant date fair value per unit \| $ / EquityUnit		13.83
Weighted average warrants for common stock \| shares		218
Weighted average contingently convertible shares \| shares		39,205
Warrants for Common Stock \| Predecessor
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average exercise price per share \| $ / shares		$ 0.01
Contingently Convertible Shares \| Predecessor
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average exercise price per share \| $ / shares		$ 12.32

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