Reconciliations of Equity - Reconciliations of Total Equity (Parenthetical) (Detail) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Number of shares of common stock issued under stock option plan	1,133	10,779	2,647	16,565
Number of common stock shares purchased	69,734	73,745	167,940	82,045
Common stock	$ 0.335	$ 0.305	$ 0.670	$ 0.610
Common Stock [Member]
Number of shares of common stock issued under stock option plan	1,133	10,779	2,647	16,565
Additional Paid-in Capital [Member]
Number of shares of common stock issued under stock option plan	1,133	10,779	2,647	16,565
Common Treasury Stock [Member]
Number of common stock shares purchased	69,734	73,745	167,940	82,045
Retained Earnings [Member]
Common stock	$ 0.335	$ 0.305	$ 0.670	$ 0.610