Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock repurchased during period (in shares)		51,384	150,656
Stock options exercised (in shares)	4,950	5,784	42,680
Equity based compensation (in shares)	27,546	41,644	15,386
Cash dividends paid (in dollars per share)	$ 0.97	$ 0.96	$ 0.93
Common Stock
Issuance of common stock (in shares)			825,586