Revenue (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) pharmacy	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) pharmacy	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
CONCENTRATION
Number of specialty pharmacies | pharmacy	2		2
Allowance for doubtful accounts	$ 7,200,000		$ 7,200,000		$ 5,300,000
Change in estimate of uncollectible (percent)			0.50%
Change in revenue recognized due to 0.5% change in uncollectible percentage			$ 300,000
Increase (decrease) to revenues	33,718,000	$ 31,020,000	106,025,000	$ 77,712,000
COVID-19 potential impacts
CONCENTRATION
Allowance related to the potential impacts of COVID-19 (less than)					$ 100,000
Additional allowance recorded			0
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
CONCENTRATION
Increase (decrease) to revenues	$ 153,000	$ 8,000	$ (125,000)	$ 695,000