Concentrations of Credit Risk, Accounts Receivable and Related Valuation Accounts (Tables)

9 Months Ended

Sep. 30, 2018

Receivables [Abstract]

Components of Company's Accounts Receivable

The following table shows the components of the Company’s accounts receivable at September 30, 2018 and December 31, 2017 (in thousands):

	September 30,		December 31,
	2018		2017
Accounts receivable	$	—	$	85
Less: allowance for doubtful accounts		—		(42	)
Less: allowance for sales returns		—		(3	)
Total	$	—	$	40

Rollforward of Allowance for Doubtful Accounts

The following is a rollforward of the Company’s allowance for doubtful accounts (in thousands):

	Nine Months Ended September 30,
	2018			2017
Beginning balance	$	42		$	16
Net charges to expenses		(42	)		48
Utilization of allowances		—			(22	)
Ending balance	$	—		$	42