Consolidated Statements Of Changes In Stockholders’ Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statements Of Changes In Stockholders’ Equity [Abstract]
Cash dividends per common share	$ 0.80	$ 0.76	$ 0.72
Reissued restricted shares	741		20,942
Issued shares in stock offering	440,000
Issued restricted shares	13,112	19,093
Issued shares under Dividend Reinvestment Plan	6,155	7,162
Issued shares in Employee Stock Purchase Plan	7,610	10,596	10,574
Issued shares in stock option exercises	10,001	5,450	7,832
Repurchased shares in treasury stock	9,218	3,280	8,676
Reissued shares under Dividend Reinvestment Plan		2,902	11,197
Reissued shares in stock option exercises	13,470	267	15,235
Reissued restricted shares, net of forfeitures		3,215
Reissued restricted shares, forfeitures		1,950