Net Income Per Share Data - Calculation of Diluted Weighted Average Shares Outstanding (Detail) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Basic weighted average shares outstanding	13,746	13,507	13,699	13,474
Dilutive effect of outstanding stock options, non-vested restricted stock, and non-vested restricted stock units	235	244	216	305
Diluted weighted average shares outstanding	13,981	13,751	13,915	13,779