Reconciliations of Equity - Reconciliations of Total Equity (Parenthetical) (Detail) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Number of shares of common stock issued under stock option plan	2,747	38,706
Number of common stock shares purchased	89,225	900
Common stock	$ 0.28	$ 0.25
Common Stock [Member]
Number of shares of common stock issued under stock option plan	2,747	38,706
Additional Paid-in Capital [Member]
Number of shares of common stock issued under stock option plan	2,747	38,706
Treasury Stock [Member]
Number of common stock shares purchased	89,225	900
Retained Earnings [Member]
Common stock	$ 0.28	$ 0.25