Stock-Based Compensation - Summary of Stock Options (Details) - $ / shares	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	3,314	2,963	1,932,286
Share Price	$ 16.31
Chief Executive Officer [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period			800,000