CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Distribution of shares of treasury stock for directors' deferred compensation (in shares)	36,681	2,438	3,740
Distribution of shares of treasury stock granted for employee restricted stock awards (in shares)	14,425	10,161	8,249
Cash dividends declared (in dollars per share)	$ 1.04	$ 1.04	$ 1.04
Distribution of shares of treasury stock for directors' compensation (in shares)	6,015	7,880	9,532
Distribution of shares of treasury stock for employee compensation (in shares)	1,784	5,861	7,661
Sale of shares of treasury stock (in shares)	14,081	14,707	15,308
Purchase of shares of treasury stock (in shares)	2,736	1,159	612
Restricted stock awards, forfeited (in shares)		1,139