Quarterly report pursuant to Section 13 or 15(d)

Summary of Share-Based Compensation Expense (Detail)

v3.8.0.1
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, 2017
tranche
shares
Sep. 30, 2016
USD ($)
Sep. 12, 2016
USD ($)
Sep. 30, 2017
USD ($)
shares
Sep. 12, 2016
USD ($)
Sep. 30, 2017
USD ($)
$ / shares
shares
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
[1] 1 Amounts for the period from July 1, 2016 through September 12, 2016 periods have been recasted (see Note 2).