Stockholder's Equity Parenthetical (Parentheticals) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Cash Dividends Paid, per Share	$ 0.98	$ 0.95	$ 0.93
Stock Dividends - Shares	538,100	522,425	341,400
Stock Options Exercised - Shares	57,756	109,651	43,096
Shares Issued Under Directors Stock Plan - Shares	6,828	6,005	8,480
Shares Issued Under the Employee Stock Purchase Plan - Shares	15,025	17,113	19,036
Shares Issued for Dividend Reinvestment Plans - Shares	49,605	55,432	32,171
Purchase of Treasury Stock - Shares	96,496	72,723	55,368
Allocation of ESOP Stock - Shares	10,407	36,927	17,645