Summary of Significant Accounting Policies - Accounts Receivable, Net and Concentration of Credit Risk (Details) - Customer Concentration Risk	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Percentage of Net Product Sales
Accounts Receivable, Net
Concentration risk percentage	89.00%	98.00%	98.00%
Percentage of Net Product Sales | Customer A
Accounts Receivable, Net
Concentration risk percentage	29.00%	32.00%	33.00%
Percentage of Net Product Sales | Customer B
Accounts Receivable, Net
Concentration risk percentage	31.00%	32.00%	33.00%
Percentage of Net Product Sales | Customer C
Accounts Receivable, Net
Concentration risk percentage	29.00%	34.00%	32.00%
Percentage of Accounts Receivable, net
Accounts Receivable, Net
Concentration risk percentage	85.00%	96.00%
Percentage of Accounts Receivable, net | Customer A
Accounts Receivable, Net
Concentration risk percentage	31.00%	45.00%
Percentage of Accounts Receivable, net | Customer B
Accounts Receivable, Net
Concentration risk percentage	32.00%	21.00%
Percentage of Accounts Receivable, net | Customer C
Accounts Receivable, Net
Concentration risk percentage	22.00%	30.00%