Quarterly report pursuant to Section 13 or 15(d)

Stock Based Compensation (Details)

v3.10.0.1
Stock Based Compensation (Details) - Employee Stock Option [Member] - $ / shares
 9 Months Ended 12 Months Ended
Sep. 30, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Shares - Nonvested, Beginning Balance (in shares) 30,690 28,465
Shares - Granted (in shares) 4,433 4,575
Shares - Vested (in shares) (7,700) (1,625)
Shares - Forfeited (in shares) 0 (725)
Shares - Nonvested, Ending Balance (in shares) 27,423 30,690
Weighted-Average Grant Date Fair Value - Nonvested, Beginning Balance (in dollars per share) $ 28.51 $ 26.67
Weighted-Average Grant Date Fair Value - Granted (in dollars per share) 43.50 39.00
Weighted-Average Grant Date Fair Value - Vested (in dollars per share) 22.64 25.81
Weighted-Average Grant Date Fair Value - Forfeited (in dollars per share) 0 28.62
Weighted-Average Grant Date Fair Value - Nonvested, Ending Balance (in dollars per share) $ 32.58 $ 28.51