Deferred Revenue

9 Months Ended

Sep. 30, 2019

Deferred Revenue Disclosure [Abstract]

Deferred Revenue

Note 12. Deferred Revenue

Deferred revenue, consisting of individually immaterial amounts for extended warranty, enhanced maintenance and advanced payments on non-recurring engineering services contracts, represents revenue that has not yet been recognized.

The following table presents the changes in deferred revenue for the periods presented (in thousands):

	Nine Months Ended September 30,
	2019			2018
Balance at beginning of period	$	834		$	1,215
Deferral of revenue		544			559
Recognition of deferred revenue		(430	)		(847	)
Balance at end of period	$	948		$	927