Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation (Details)

v3.19.1
Share-Based Compensation (Details)
$ / shares in Units, $ in Millions
3 Months Ended
Jan. 18, 2019
shares
Jan. 01, 2019
USD ($)
$ / shares
shares
Mar. 31, 2019
USD ($)
Percentile_Rank
Form
$ / shares
shares
PIUs      
Share-Based Compensation      
Number of forms of executive compensation | Form     2
Time-based PIU's      
Share-Based Compensation      
Stock awards granted (in shares or units) | shares     54,956
Aggregate grant date fair value | $     $ 1.4
Aggregate grant date fair value (in dollars per share) | $ / shares     $ 25.81
Annual award vesting rights (percent)     33.33%
Award vesting period     3 years
Restricted shares      
Share-Based Compensation      
Stock awards granted (in shares or units) | shares     135,396
Aggregate grant date fair value | $     $ 3.5
Aggregate grant date fair value (in dollars per share) | $ / shares     $ 25.81
Shares vested (in shares) | shares     151,252
Weighted average fair value of shares vested (in dollars per share) | $ / shares     $ 27.94
Aggregate intrinsic value of awards upon vesting | $     $ 3.9
2016 PSU Grants | Performance share units | Executives      
Share-Based Compensation      
Shares issued (in shares) | shares 44,757    
Percentage of target 157.00%    
2019 PIU Grants | Performance-based PIU's      
Share-Based Compensation      
Stock awards granted (in shares or units) | shares   193,682  
Aggregate grant date fair value | $   $ 2.4  
Aggregate grant date fair value (in dollars per share) | $ / shares   $ 12.47  
Award vesting period   3 years  
Potential earned PSUs payout for defined levels of performance under awards      
Earned PB-PIUs payout (as a percent of PB-PIUs granted) on 75th or greater percentile rank   100.00%  
Earned PB-PIUs payout (as a percent of PB-PIUs granted) on 50th percentile rank   50.00%  
Earned PB-PIUs payout (as a percent of PB-PIUs granted) on 25th percentile rank   25.00%  
Earned PB-PIUs granted on percentile rank below 25th (as a percent)   0.00%  
The number of percentile ranks to fall between to earn interpolated PB-PIUs between such percentile ranks, conditioned on the percentile rank exceeding 25% | Percentile_Rank     2
Assumptions used to value stock awards      
Percent of award distribution rights     10.00%
Award performance period     3 years
Baseline value per common share (in dollars per share) | $ / shares   $ 21.03  
Expected volatility of common shares (as a percent)   21.00%  
Risk-free interest rate (as a percent)   2.51%