CONSOLIDATED STATEMENTS OF EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CONSOLIDATED STATEMENTS OF EQUITY
Issuance of shares of common stock upon exercise of stock options		17,000	158,021
Purchase of shares of common stock	161,500	45,807	171,907
Dividends declared on common stock (dollars per per share)	$ 0.68	$ 0.68	$ 0.68