Revenue (Tables)

3 Months Ended

Mar. 31, 2019

Revenue From Contract With Customer [Abstract]

Schedule of Disaggregation of Revenue

The following table presents the Company’s revenue disaggregated by revenue source:

	Three Months Ended
	March 31,
	2019		2018
Systems	$	42,772	$	56,102
Software licensing, support and maintenance		7,037		7,455
Parts		8,077		6,985
Services		3,006		2,554
Total revenue	$	60,892	$	73,096

The following table represents a disaggregation of revenue by timing of revenue:

	Three Months Ended
	March 31,
	2019		2018
Point-in-time	$	56,591	$	69,396
Over-time		4,301		3,700
Total revenue	$	60,892	$	73,096

Schedule of Changes in Deferred Revenue

Changes in deferred revenue were as follows:

	Three Months Ended
	March 31,
	2019			2018
Balance, beginning of the period	$	8,080		$	7,206
Deferral of revenue		1,805			4,553
Recognition of deferred revenue		(1,198	)		(2,986	)
Balance, ending of the period	$	8,687		$	8,773