Supplemental Cash Flow Information - Cash Payments and Non-Cash Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental cash flow information:
Cash paid for interest	$ 21	$ 6	$ 4
Cash paid for income taxes	3,409	5,498	5,813
Supplemental noncash investing and financing activities:
Transfer of service and sales demonstration inventory to fixed assets	1,688	3,044	964
Assumption of contingent consideration from acquisition	$ 980	$ 0	$ 6,751