Segment Information - Concentration Risk (Details) - distributor	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Information
Number of distributors	3	3	3	3
Net revenues | Customer concentration | Distributor 1
Segment Information
Concentration risk, percentage	48.00%	55.00%	50.00%	55.00%
Net revenues | Customer concentration | Distributor 2
Segment Information
Concentration risk, percentage	29.00%	29.00%	27.00%	27.00%
Net revenues | Customer concentration | Distributor 3
Segment Information
Concentration risk, percentage	11.00%	8.00%	11.00%	8.00%