Revenue Recognition - Summary of Product Revenue Allowance and Reserve Categories (Detail) - HEPLISAV-B® $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Product Revenue Allowance and Revenue Categories [Line Items]
Provision related to current period sales	$ 943
Credit or payments made during the period	(262)
Balance at June 30, 2018	681
Chargebacks, Discounts and Other Fees
Product Revenue Allowance and Revenue Categories [Line Items]
Provision related to current period sales	825
Credit or payments made during the period	(262)
Balance at June 30, 2018	563
Returns
Product Revenue Allowance and Revenue Categories [Line Items]
Provision related to current period sales	118
Balance at June 30, 2018	$ 118