Product Revenue - Schedule of Product Revenue Allowance and Reserves (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Contractual Adjustments [Roll Forward]
Contract adjustments, beginning balance	$ 592
Contractual adjustments, current provisions relating to sales in the current year	5,596
Contractual adjustments, adjustments relating to prior year	8
Contractual adjustments, payments/returns relating to sales in the current year	(4,583)
Contractual adjustments, payments/returns relating to sales in the prior year	(598)
Contract adjustments, ending balance	1,015
Government Rebates [Roll Forward]
Government rebates, beginning balance	325
Government rebates, current provisions relating to sales in the current year	1,402
Government rebates, adjustments relating to prior years	(48)
Government rebates, payments/returns relating to sales in the current year	(714)
Government rebates, payments/returns relating to sales in the prior years	(261)
Government rebates, ending balance	704
Product Returns [Roll Forward]
Returns, beginning balance	334
Returns, current provisions relating to sales in the current year	1,003
Returns, adjustments relating to prior years	0
Returns, payments/returns relating to sales in the current year	0
Returns, payments/returns relating to sales in the prior years	0
Returns, ending balance	1,337
Allowance for Doubtful Accounts Receivable [Roll Forward]
Total revenue-related reserves	3,056	$ 1,251
Total allowances and reserves, current provisions relating to sales in the current year	8,001
Total allowances and reserves, adjustments relating to prior years	(40)
Total allowances and reserves, payments/returns relating to sales in the current year	(5,297)
Total allowances and reserves, payments/returns relating to sales in the prior years	$ (859)