Summary of Significant Accounting Policies (Revenue Recognition) (Details)	12 Months Ended
	Sep. 30, 2019
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Subscriber assets depreciation period	3 years
Minimum | Subscription revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Length Of Contract	1 year
Maximum | Subscription revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Length Of Contract	5 years