Quarterly report pursuant to Section 13 or 15(d)

Share-Based Payments - Employee Activity Performance Shares (Details)

v3.7.0.1
Share-Based Payments - Employee Activity Performance Shares (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Share-based compensation expense $ 1,962 $ 1,952
Key Employee Performance Share Based Plan [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Period of Share Price Performance Comparison to Peer Group 3 years  
Minimum percentage of peer group by which Company share price must outperform before incremental performance shares are issued 30.00%  
Percentage of Peer Group By Which Company Share Price Must Outperform Before Maximum Incremental Shares Are Issued 90.00%  
Expected Stock Price Volatility Rate 24.70% 22.30%
Weighted Average Risk Free Interest Rate 1.40% 0.80%
Outstanding and non-vested, beginning of period (in shares) 80  
Grants in Period 25  
Shares Forfeited in Period (29)  
Outstanding and non-vested, end of period (in shares) 76  
Outstanding and non-vested, weighted-average grant date fair value, beginning of period $ 55  
Grants in Period, Weighted Average Grant Date Fair Value 56  
Forfeited in Period, Weighted Average Grant Date Fair Value 50  
Outstanding and non-vested, weighted-average grant date fair value, end of period $ 57  
Outstanding and non-vested, aggregate grant date fair value $ 4,327  
Share-based compensation expense 184 $ 351
Tax benefit related to share-based expense 68 131
Unrecognized share-based compensation, net of estimated forfeitures $ 2,612 $ 2,805
Weighted average period over which unrecognized compensation will be recognized (years) 2 years 2 months 11 days