Revenue Recognition

6 Months Ended

Jun. 30, 2019

Revenue Recognition [Abstract]

Revenue Recognition

9. Revenue Recognition

All of our product revenue consisted of sales of HEPLISAV-B in the U.S. For the six months ended June 30, 2019 and 2018, our three largest Customers represented approximately 64% and 56% of our product revenue, respectively. The following table summarizes balances and activity in each of the product revenue allowance and reserve categories for the six months ended June 30, 2019 (in thousands):

	Chargebacks, distribution fees, discounts and other fees			Returns			Total
Balance at December 31, 2018	$	1,736		$	569		$	2,305
Provision related to current period sales		6,418			1,071			7,489
Credit or payments made during the period		(4,698	)		(217	)		(4,915	)
Balance at June 30, 2019	$	3,456		$	1,423		$	4,879

Reserves for chargebacks and discounts totaling $2.5 million were recorded as reductions of accounts receivable at June 30, 2019. The remaining reserves balances totaling $2.4 million were recorded as accrued liabilities at June 30, 2019.