Product Revenue Reserves and Allowances - Product Revenue Allowance and Reserves (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Disclosure of Product Revenue Reserves and Allowances [Line Items]
Beginning balance at January 1, 2019	$ 0
Provision related to sales in the current year	3,462
Deductions applied and payments made	(1,221)
Ending balance at December 31, 2019	2,241
Chargebacks, Discounts and Fees [Member]
Disclosure of Product Revenue Reserves and Allowances [Line Items]
Beginning balance at January 1, 2019	0
Provision related to sales in the current year	2,301
Deductions applied and payments made	(683)
Ending balance at December 31, 2019	1,618
Government and Other Rebates [Member]
Disclosure of Product Revenue Reserves and Allowances [Line Items]
Beginning balance at January 1, 2019	0
Provision related to sales in the current year	429
Deductions applied and payments made	(158)
Ending balance at December 31, 2019	271
Returns [Member]
Disclosure of Product Revenue Reserves and Allowances [Line Items]
Beginning balance at January 1, 2019	0
Provision related to sales in the current year	732
Deductions applied and payments made	(380)
Ending balance at December 31, 2019	$ 352