Common Stock Common Stock (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payment, Tax Withholding, Share-based Payment Arrangement	$ (800,000)	$ (600,000)	$ (9,300,000)	$ (16,400,000)
Payments for Repurchase of Common Stock			$ (130,700,000)	$ (54,100,000)