Quarterly report pursuant to Section 13 or 15(d)

Summary of Share-Based Compensation Expense (Detail)

v3.7.0.1
Summary of Share-Based Compensation Expense (Detail)
$ / shares in Units, $ in Thousands
1 Months Ended 3 Months Ended 6 Months Ended
Jan. 31, 2017
tranche
$ / shares
shares
Jun. 30, 2017
USD ($)
shares
Jun. 30, 2016
USD ($)
Jun. 30, 2017
USD ($)
$ / shares
shares
Jun. 30, 2016
USD ($)
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]          
Share-based compensation (equity-classified)       $ (1,700)  
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   256,400   256,400  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares       $ 51.50  
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 62,675 62,675   62,675  
Share-based Compensation Arrangements By Share-based Payment Award, Award Amortization Period 5 years        
Share-based Compensation Arrangements By Share-based Payment Award, Number Of Award Tranches | tranche 3        
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       1.49%  
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, 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, Shares, Expected to Vest, Percentage 200.00%        
Performance Restricted Stock Units [Domain] | Year 1 [Domain]          
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        
Performance Restricted Stock Units [Domain] | Year 2          
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 61.74        
Performance Restricted Stock Units [Domain] | Year 3          
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 $ 61.74        
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   148,837   148,837  
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     $ 1,965   $ 1,364
Share-based compensation (equity-classified)         (1,364)
Allocated Share-based Compensation Expense     1,953   1,345
Defined Contribution Plan, Cost     200   300
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   100
Predecessor [Member] | Liability-classified awards          
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]          
Share-based compensation (equity-classified)     $ (12)   $ (19)
Successor [Member]          
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]          
Other Stock Based Compensation Expense   $ 848   $ 1,694  
Share-based compensation (equity-classified)       (1,694)  
Allocated Share-based Compensation Expense   848   1,694  
Defined Contribution Plan, Cost   100   200  
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