Earnings Per Share Data - Additional Information (Detail) - shares	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Exercisable stock options, included in the diluted earnings per share calculation	250,000	317,000	257,000	317,000
Effect of dilutive stock options	118,000	164,000	125,000	163,000
Inclusive Of Diluted Earning [Member]
Exercisable stock options, included in the diluted earnings per share calculation			7,000
Effect of dilutive stock options	7,000
Anti-dilutive shares	0	0	0	0