Stockholders' Equity - Narrative (Details) - USD ($)	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2021	Dec. 31, 2018
Equity [Abstract]
Preferred stock outstanding (in shares)			0
Common stock authorized (in shares)	63,000,000		63,000,000
Common stock issued (in shares)	31,012,326		31,294,198
Common stock outstanding (in shares)	31,012,326		31,294,198
Authorized amount repurchase of common stock				$ 50,000,000
Aggregate repurchased value	$ 3,327,000	$ 34,624,000
Remaining availability repurchase amount			$ 12,000,000
382 ownership limitation			4.95%