Common Stock Common Stock (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payment, Tax Withholding, Share-based Payment Arrangement	$ 600,000	$ (200,000)	$ (16,400,000)	$ (4,200,000)
Payments for Repurchase of Common Stock			$ 54,100,000	$ (75,000,000.0)