Consolidated Statements of Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of shares of common stock issued under stock option plan	59,799	97,471	104,277
Number of common stock shares purchased	144,457	205,983	76,790
Common stock	$ 1.03	$ 0.93	$ 0.86
Common Stock [Member]
Number of shares of common stock issued under stock option plan	59,799	97,471	104,277
Additional Paid-in Capital [Member]
Number of shares of common stock issued under stock option plan	59,799	97,471	104,277
Treasury Stock [Member]
Number of common stock shares purchased	144,457	205,983	76,790