Share-based Compensation - Award Status (Details) - Stock option awards	3 Months Ended
	Mar. 31, 2019 $ / shares shares
Shares
Outstanding at beginning of year (in shares) | shares	87,600
Exercised (in shares) | shares	(8,712)
Forfeited (in shares) | shares	(1,319)
Expired (in shares) | shares	(176)
Outstanding at end of year (in shares) | shares	77,393
Exercisable at end of year (in shares) | shares	61,146
Weighted-Average Exercise Price
Outstanding at beginning of year (in dollars per share) | $ / shares	$ 20.58
Exercised (in dollars per share) | $ / shares	12.93
Forfeited (in dollars per share) | $ / shares	23.53
Expired (in dollars per share) | $ / shares	21.03
Outstanding at end of year (in dollars per share) | $ / shares	21.39
Exercisable at end of year (in dollars per share) | $ / shares	$ 20.82
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	4 years 6 months
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	5 years 1 month 28 days