CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Distribution of shares of treasury stock for directors' deferred compensation (in shares)	6,426	2,551	36,681
Distribution of shares of treasury stock granted for employee restricted stock awards (in shares)	14,805	13,692	14,425
Cash dividends declared (in dollars per share)	$ 1.04	$ 1.04	$ 1.04
Distribution of shares of treasury stock for directors' compensation (in shares)	7,923	8,465	6,015
Distribution of shares of treasury stock for employee compensation (in shares)	2,274	2,373	1,784
Sale of shares of treasury stock (in shares)	36,104	13,270	14,081
Purchase of shares of treasury stock (in shares)	257,018	4,148	2,736
Restricted stock awards, forfeited (in shares)	112