Trade Accounts Receivable (Tables)

3 Months Ended

Mar. 31, 2018

Receivables [Abstract]

Summary of Trade Accounts Receivable

Trade accounts receivable are recorded at the invoiced amount.

	March 31,			December 31,
	2018			2017
Trade accounts receivable	$	3,805		$	6,419
Allowance for doubtful accounts		(15	)		(15	)
Trade accounts receivable, net	$	3,790		$	6,404
Unpaid deferred revenue included in trade    accounts receivable	$	909		$	2,217

Customers Accounted for 10% or More of Trade Accounts Receivable, Net

The following customers accounted for 10% or more of trade accounts receivable, net:

	March 31,			December 31,
	2018			2017
Central Banks		60	%		47	%