Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.1
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 12 Months Ended
Jan. 31, 2017
tranche
Mar. 31, 2019
USD ($)
$ / shares
shares
Mar. 31, 2018
USD ($)
$ / shares
shares
Dec. 31, 2018
USD ($)
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]        
Dividends | $   $ 0 $ 0  
Share-based compensation (equity-classified) | $   1,038 1,576  
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost | $     600  
Separation Agreement, Consulting Fees | $       $ 300
Defined Contribution Plan, Cost | $   200 $ 100  
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    
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 | shares   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     $ 36.52  
Shares, Issued | shares   24,657 37,845  
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 | shares   0 98,526  
Share-based Compensation Arrangements By Share-based Payment Award, Award Amortization Period   5 years    
Shares, Issued | shares   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 | shares   0 5,719  
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