Stock-Based Compensation - Restricted Stock Units Granted - Tabular Disclosure (Details) - shares	6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stocks granted (in shares)	329,801	408,827
Restricted Stock, Time Based Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stocks granted (in shares)	149,249	163,390
Board of Director Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stocks granted (in shares)	14,657	23,867
Restricted Stock, Performance Based Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stocks granted (in shares)	165,895	221,570