Revenues - Summary of the Percentage of Total Revenues from Customers (Details) - Total Revenues - Customer concentration risk	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Express Scripts
Concentration Risk [Line Items]
Percentage of total revenues (as a percent)	74.00%	79.00%	77.00%	76.00%
McKesson
Concentration Risk [Line Items]
Percentage of total revenues (as a percent)	10.00%	12.00%	11.00%	14.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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