Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation and Other Compensation Matters (Details)

v3.7.0.1
Share-Based Compensation and Other Compensation Matters (Details)
$ / shares in Units, $ in Thousands
 6 Months Ended
Feb. 07, 2017
shares
Jan. 01, 2017
USD ($)
Percentile_Rank
$ / shares
shares
Jun. 30, 2017
USD ($)
$ / shares
shares
Other Share-based Compensation Additional Disclosures      
Options exercised in period (in shares or units)     5,000
Restricted shares      
Share-Based Compensation      
Stock awards granted (in shares or units)     227,235
Aggregate grant date fair value | $     $ 7,700
Assumptions used to value stock awards      
Weighted average grant date fair value (in dollars per share) | $ / shares     $ 33.97
Other Share-based Compensation Additional Disclosures      
Shares vested (in shares)     144,006
Weighted average fair value of shares vested (in dollars per share) | $ / shares     $ 26.22
Aggregate intrinsic value of awards upon vesting | $     $ 4,900
Deferred share awards      
Share-Based Compensation      
Stock awards granted (in shares or units)     10,032
Aggregate grant date fair value | $     $ 326
Assumptions used to value stock awards      
Weighted average grant date fair value (in dollars per share) | $ / shares     $ 32.47
Other Share-based Compensation Additional Disclosures      
Shares vested (in shares)     15,590
Weighted average fair value of shares vested (in dollars per share) | $ / shares     $ 26.89
Aggregate intrinsic value of awards upon vesting | $     $ 508
Options      
Other Share-based Compensation Additional Disclosures      
Options exercised in period (in shares or units)     5,000
Options exercised weighted average exercise price (in dollars per share) | $ / shares     $ 29.98
Intrinsic value of options exercised | $     $ 18
2017 PSU Grants | Performance share units      
Share-Based Compensation      
Stock awards granted (in shares or units)   36,525  
Aggregate grant date fair value | $   $ 1,400  
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   $ 38.43  
Baseline value per common share (in dollars per share) | $ / shares   $ 31.22  
Expected volatility of common shares (as a percent)   19.00%  
Risk-free interest rate (as a percent)   1.47%  
2014 PSU Grants | Performance share units | Chief Executive Officer      
Other Share-based Compensation Additional Disclosures      
Shares issued (in shares) 9,763    
Percentage of target 100.00%