Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation and Other Benefit Plans - Summary of Share-Based Compensation Expense (Details)

v3.10.0.1
Share-Based Compensation and Other Benefit Plans - Summary of Share-Based Compensation Expense (Details)
$ / shares in Units, $ in Thousands
1 Months Ended 3 Months Ended 9 Months Ended
Jan. 31, 2017
tranche
Sep. 30, 2018
USD ($)
shares
Sep. 30, 2017
USD ($)
shares
Sep. 30, 2018
USD ($)
$ / shares
shares
Sep. 30, 2017
USD ($)
$ / shares
shares
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]          
Share-based compensation (equity-classified) | $   $ 1,000 $ 1,000 $ 3,472 $ 2,707
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost | $       600  
Defined Contribution Plan, Cost | $   100 200 400 300
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) | $   $ 0 $ 0 $ 100 $ 100
Time Vested Restricted Stock Units [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   347,440   347,440  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares       $ 65.96 $ 48.70
Shares, Issued   53,411 12,252 53,411 12,252
Time Vested Restricted Stock Units [Member] | Minimum [Member]          
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]          
Share-based Compensation Arrangements By Share-based Payment Award, Award Amortization Period       4 years  
Time Vested Restricted Stock Units [Member] | Maximum [Member]          
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]          
Share-based Compensation Arrangements By Share-based Payment Award, Award Amortization Period       5 years  
Performance Restricted Stock Units [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   0 98,526 0 98,526
Share-based Compensation Arrangements By Share-based Payment Award, Award Amortization Period       5 years  
Shares, Issued   1,495   1,495  
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 [Member] | Minimum [Member]          
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]          
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%  
Share-based Compensation Arrangement by Share-based Payment Award, Terms of Award       0.5963  
Performance Restricted Stock Units [Member] | Maximum [Member]          
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]          
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%  
Share-based Compensation Arrangement by Share-based Payment Award, Terms of Award       0.6218  
Performance Restricted Stock Units [Member] | Year 1 [Member] | 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 [Member] | Year 2 [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 [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   42,459 190,891 42,459 190,891
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   749,600   749,600