Stock-Based Compensation - Restricted Stock Units Granted - Tabular Disclosure (Details) - shares	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stocks granted (in shares)	745,776	471,151
Restricted Stock, Time Based Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stocks granted (in shares)	321,835	190,266
Board of Director Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stocks granted (in shares)	552	546
Restricted Stock, Performance Based Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stocks granted (in shares)	423,389	280,339