Basis of presentation and summary of significant accounting policies - Additional Information (Details)	Sep. 30, 2021 USD ($)
Financing Agreement [Member] | Forecasted Debt Covenant Compliance [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Minimum cash balance requirement under credit agreement	$ 60,000,000.0
VitaCare Prescription Services [Member] | COVID-19 [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Cost savings initiative to reduce annual costs	20,000,000.0
Minimum [Member] | COVID-19 [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Cost savings initiative to reduce annual costs	$ 40,000,000.0