Summary of Share-Based Compensation Expense (Detail) $ / shares in Units, $ in Thousands | 1 Months Ended | 2 Months Ended | 3 Months Ended | 8 Months Ended | 9 Months Ended |
Jan. 31, 2017trancheshares | Sep. 30, 2016USD ($) | Sep. 12, 2016USD ($) | Sep. 30, 2017USD ($)shares | Sep. 12, 2016USD ($) | Sep. 30, 2017USD ($)$ / sharesshares |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | | | | | | | |
Share-based compensation (equity-classified) | | | | | | | $ (2,700) |
Time Vested Restricted Stock Units [Domain] | | | | | | | |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | shares | | | | | 298,454 | | 298,454 |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares | | | | | | | $ 48.70 |
Share-based Compensation Arrangements By Share-based Payment Award, Award Amortization Period | | | | | | | 5 years |
Performance Restricted Stock Units [Domain] | | | | | | | |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | shares | 98,526 | | | | | | |
Share-based Compensation Arrangements By Share-based Payment Award, Award Amortization Period | 5 years | | | | | | |
Share-based Compensation Arrangements By Share-based Payment Award, Performance Period | 3 years | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum | | | | | | | 1.44% |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum | | | | | | | 1.51% |
Performance Restricted Stock Units [Domain] | Minimum [Member] | | | | | | | |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Terms of Award | | | | | | | 0.5963 |
Share-based Compensation Arrangements By Share-based Payment Award, Number Of Award Tranches | tranche | 2 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Shares, Expected to Vest, Percentage | 0.00% | | | | | | |
Performance Restricted Stock Units [Domain] | Maximum [Member] | | | | | | | |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Terms of Award | | | | | | | 0.6218 |
Share-based Compensation Arrangements By Share-based Payment Award, Number Of Award Tranches | tranche | 3 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Shares, Expected to Vest, Percentage | 200.00% | | | | | | |
Performance Restricted Stock Units [Domain] | Year 1 [Domain] | Minimum [Member] | | | | | | | |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares | | | | | | | $ 47.70 |
Performance Restricted Stock Units [Domain] | Share-based Compensation Award, Tranche Two [Member] | Maximum [Member] | | | | | | | |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares | | | | | | | $ 65.28 |
Time Vested Restricted Stock Units - Employees [Domain] [Domain] | | | | | | | |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | shares | | | | | 190,891 | | 190,891 |
Employees and Directors [Member] | | | | | | | |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | shares | | | | | 749,600 | | 749,600 |
Predecessor [Member] | | | | | | | |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | | | | | | | |
Other Stock Based Compensation Expense | | | $ 147 | [1] | | $ 1,511 | |
Share-based compensation (equity-classified) | | | | | | (1,511) | |
Allocated Share-based Compensation Expense | | | 147 | | | 1,492 | |
Defined Contribution Plan, Cost | | | | | | 400 | |
Predecessor [Member] | 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 | |
Predecessor [Member] | Liability-classified awards | | | | | | | |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | | | | | | | |
Share-based compensation (equity-classified) | | | $ 0 | | | $ 19 | |
Successor [Member] | | | | | | | |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | | | | | | | |
Other Stock Based Compensation Expense | | $ 0 | | | $ 1,013 | | $ 2,707 |
Share-based compensation (equity-classified) | | 0 | | | | | (2,707) |
Allocated Share-based Compensation Expense | | 0 | | | 1,013 | | 2,707 |
Defined Contribution Plan, Cost | | 100 | | | | | 300 |
Successor [Member] | 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 | | | | | 100 |
Successor [Member] | Liability-classified awards | | | | | | | |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | | | | | | | |
Share-based compensation (equity-classified) | | $ 0 | | | $ 0 | | $ 0 |
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[1] | 1 Amounts for the period from July 1, 2016 through September 12, 2016 periods have been recasted (see Note 2). |