CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Distribution of shares of treasury stock for directors' deferred compensation (in shares)	2,551	36,681	2,438
Distribution of shares of treasury stock granted for employee restricted stock awards (in shares)	13,692	14,425	10,161
Cash dividends declared (in dollars per share)	$ 1.04	$ 1.04	$ 1.04
Distribution of shares of treasury stock for directors' compensation (in shares)	8,465	6,015	7,880
Distribution of shares of treasury stock for employee compensation (in shares)	2,373	1,784	5,861
Sale of shares of treasury stock (in shares)	13,270	14,081	14,707
Purchase of shares of treasury stock (in shares)	4,148	2,736	1,159
Restricted stock awards, forfeited (in shares)			1,139