CONSOLIDATED STATEMENTS OF EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CONSOLIDATED STATEMENTS OF EQUITY
Issuance of shares of common stock upon exercise of stock options	17,000	158,021	158,021
Purchase of shares of common stock	45,807	171,907	171,907
Dividends declared on common stock (dollars per per share)	$ 0.68	$ 0.68	$ 1.02