Segment Information - Concentration Risk (Details) - distributor	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Information
Number of distributors	3	3	3	3
Net revenues | Customer concentration | Distributor 1
Segment Information
Concentration risk, percentage	49.00%	56.00%	50.00%	56.00%
Net revenues | Customer concentration | Distributor 2
Segment Information
Concentration risk, percentage	30.00%	28.00%	28.00%	27.00%
Net revenues | Customer concentration | Distributor 3
Segment Information
Concentration risk, percentage	10.00%	10.00%	11.00%	8.00%