Summary of Significant Accounting Policies - Concentrations of Credit Risk (Details)	12 Months Ended
	Sep. 30, 2020
Walgreens Boots Alliance, Inc.
Concentration Risk [Line Items]
Major customer, percentage of revenue	33.00%
Major customer, percentage of accounts receivable	47.00%
Express Scripts, Inc.
Concentration Risk [Line Items]
Major customer, percentage of revenue	12.00%
Major customer, percentage of accounts receivable	7.00%