Supplemental Cash Flow Information (Tables)

12 Months Ended

Dec. 31, 2017

Supplemental Cash Flow Elements [Abstract]

Schedule of cash Payments and Non-Cash Activity

Selected cash payments and non-cash activities were as follows:

	Years ended December 31,
	2017		2016		2015
Supplemental cash flow information:
Cash paid for interest	$	9	$	28	$	55
Cash paid for income taxes	$	2,488	$	2,576	$	4,682
Supplemental noncash investing and financing activities:
Transfer of service and sales demonstration inventory to fixed assets	$	2,844	$	511	$	2,979