Quarterly report pursuant to Section 13 or 15(d)

Share-Based Payments - Non-employee Director Non-vested Shares (Details)

v3.8.0.1
Share-Based Payments - Non-employee Director Non-vested Shares (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Non-Employee Director Shares, Vesting Period (in years) 1 year  
Share-based compensation expense $ 2,261 $ 1,962
Nonemployee Director Nonvested Shares Granted Member    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Outstanding and non-vested, beginning of period (in shares) 11  
Grants in Period 1  
Shares Vested in Period 0  
Shares Forfeited in Period 0  
Outstanding and non-vested, end of period (in shares) 12  
Outstanding and non-vested, weighted-average grant date fair value, beginning of period $ 52  
Grants in Period, Weighted Average Grant Date Fair Value 61  
Vested in Period, Weighed-average grant date fair value 0  
Forfeited in Period, Weighted Average Grant Date Fair Value 0  
Outstanding and non-vested, weighted-average grant date fair value, end of period $ 52  
Outstanding and non-vested, aggregate grant date fair value $ 615  
Share-based compensation expense 185 169
Tax benefit related to share-based expense 47 63
Unrecognized share-based compensation, net of estimated forfeitures $ 65 $ 77
Weighted average period over which unrecognized compensation will be recognized (years) 1 month 11 days