Consolidated Statements Of Changes In Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Cash dividends declared	$ 1.78	$ 1.72	$ 1.68
Exercise of stock options	16,639	32,750	81,500
Stock Issued During Period, Shares, Other	0	0	61,796
Stock Issued During Period, Shares, New Issues	440,604	107,662	0
Purchase of treasury shares	0	231,132	150,385