Consolidated Statements Of Changes In Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Consolidated Statements Of Changes In Shareholders' Equity [Abstract]
Cash dividends per share	$ 0.155	$ 0.129
Issuance and reissuance of common stock:
Shares under the dividend reinvestment and stock purchase plan	5,518	4,383
Shares under the stock option plan	13,736
Shares of stock-based compensation awards	1,816	2,445