Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation (Details)

v3.10.0.1
Share-Based Compensation (Details)
$ / shares in Units, $ in Thousands
 6 Months Ended
Feb. 22, 2018
shares
Jan. 01, 2018
USD ($)
employee
Percentile_Rank
$ / shares
shares
Jun. 30, 2018
USD ($)
$ / shares
shares
Restricted shares      
Share-Based Compensation      
Stock awards granted (in shares or units) | shares     196,366
Aggregate grant date fair value | $     $ 5,000
Assumptions used to value stock awards      
Weighted average grant date fair value (in dollars per share) | $ / shares     $ 25.38
Other Share-based Compensation Additional Disclosures      
Shares vested (in shares) | shares     161,322
Weighted average fair value of shares vested (in dollars per share) | $ / shares     $ 29.72
Aggregate intrinsic value of awards upon vesting | $     $ 4,100
Deferred share awards      
Share-Based Compensation      
Stock awards granted (in shares or units) | shares     13,832
Aggregate grant date fair value | $     $ 388
Assumptions used to value stock awards      
Weighted average grant date fair value (in dollars per share) | $ / shares     $ 28.08
Other Share-based Compensation Additional Disclosures      
Shares vested (in shares) | shares     5,515
Weighted average fair value of shares vested (in dollars per share) | $ / shares     $ 29.32
Aggregate intrinsic value of awards upon vesting | $     $ 154
2018 PSU Grants | Performance share units      
Share-Based Compensation      
Stock awards granted (in shares or units) | shares   59,110  
Aggregate grant date fair value | $   $ 1,900  
Potential earned PSUs payout for defined levels of performance under awards      
Earned PSUs payout (as a percent of PSUs granted) on 75th or greater percentile rank   200.00%  
Earned PSUs payout (as a percent of PSUs granted) on 50th percentile rank   100.00%  
Earned PSUs payout (as a percent of PSUs granted) on 25th percentile rank   50.00%  
Performance share units granted on percentile rank below 25th (as a percent)   0.00%  
The number of percentile ranks to fall between to earn interpolated PSUs between such percentile ranks, conditioned on the percentile rank exceeding 25% | Percentile_Rank   2  
Assumptions used to value stock awards      
Performance period of the award   3 years  
Weighted average grant date fair value (in dollars per share) | $ / shares   $ 31.97  
Baseline value per common share (in dollars per share) | $ / shares   $ 29.20  
Expected volatility of common shares (as a percent)   17.00%  
Risk-free interest rate (as a percent)   2.04%  
2018 PSU Grants | Performance share units | Executives      
Share-Based Compensation      
Number of employees affected | employee   3  
2015 PSU Grants | Performance share units | Executives      
Other Share-based Compensation Additional Disclosures      
Shares issued (in shares) | shares 13,328    
Percentage of target 75.00%