Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Amount of cost (reversal of cost) for pension and other postretirement benefits.

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Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans, classified as noncurrent.

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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Share-Based Compensation and Other Benefit Plans (Detail) - USD ($) $ in Thousands	4 Months Ended	8 Months Ended	12 Months Ended
	Dec. 31, 2016	Sep. 12, 2016	Dec. 31, 2018	Dec. 31, 2017
Successor [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation (equity-classified)	$ 81		$ 4,618	$ 3,809
Allocated Share-based Compensation Expense	81		4,618	3,809
Successor [Member] \| Restricted Stock Units (RSUs)
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized			$ 7,800
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			42,459
Successor [Member] \| Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			1 year 5 months 26 days
Predecessor [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation (equity-classified)		$ 1,511
Allocated Share-based Compensation Expense		1,492
Other Pension, Postretirement and Supplemental Plans [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Pension and Other Postretirement Benefits Cost (Reversal of Cost)				100
Other Pension, Postretirement and Supplemental Plans [Member] \| Successor [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Liability, Defined Benefit Plan, Noncurrent			$ 1,400	$ 1,700
Pension and Other Postretirement Benefits Cost (Reversal of Cost)	$ 100		$ 100
Other Pension, Postretirement and Supplemental Plans [Member] \| Predecessor [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Pension and Other Postretirement Benefits Cost (Reversal of Cost)		$ 100