Summary of Significant Accounting Policies and Select Balance Sheet Information - Denominator for Computation of Diluted Weighted Average Shares Outstanding (Detail) - shares shares in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Basic weighted average shares outstanding	13,765	13,552	13,389
Dilutive effect of outstanding stock options, non-vested restricted stock, and non-vested restricted stock units	224	260	390
Diluted weighted average shares outstanding	13,989	13,812	13,779