Revenue (Tables)

3 Months Ended

Mar. 31, 2018

Revenue From Contract With Customer [Abstract]

Schedule of Performance Obligation

Performance Obligation	When Performance Obligation is Typically Satisfied	When Payment is Typically Due	How Standalone Selling Price is Typically Estimated
Hardware products	When customer obtains control of the product (point-in-time)	Within 30-60 days of shipment	Observable in transactions without multiple performance obligations
Software licenses	When license is delivered to customer or made available for download, and the applicable license period has begun (point-in-time)	Within 30-60 days of the beginning of license period	Established pricing practices for software licenses bundled with software maintenance, which are separately observable in renewal transactions
Professional services	As services are performed and/or when contract is fulfilled (point-in-time)	Within 30-60 days of delivery	Observable in transactions without multiple performance obligations
Software maintenance    and support services	Ratably over the course of the support contract (over time)	Within 30-60 days of the beginning of the contract period	Observable in renewal transactions
Extended hardware    warranties	Ratably over the course of the support contract (over time)	Within 30-60 days of the beginning of the contract period	Observable in renewal transactions

Total Net Sales Based on Disaggregation Criteria

Total net sales based on the disaggregation criteria described above are as follows (in thousands):

	Three Months Ended March 31,
	2018						2017 (1)
	Point-in- Time		Over Time		Total		Point-in- Time		Over Time		Total
Americas	$	12,484	$	748	$	13,232	$	8,859	$	249	$	9,108
Europe and the Middle East		2,294		14		2,308		1,867		12		1,879
Asia-Pacific		985		3		988		2,403		2		2,405
Total	$	15,763	$	765	$	16,528	$	13,129	$	263	$	13,392
(1)  As discussed in Note 1, prior periods have not been adjusted for the adoption of Topic 606.

Changes in Deferred Revenue

Changes in deferred revenue during the three months ended March 31, 2018 were as follows (in thousands):

	Amount
Deferred revenue at December 31, 2017	$	1,090
Impact of adoption of Topic 606		(2	)
Deferred revenue at January 1, 2018		1,088
Fair value of deferred revenue acquired in acquisition, net of recognition		2,637
Deferral of revenue billed in current period, net of recognition		895
Recognition of revenue deferred in prior periods		(293	)
Balance as of March  31, 2018	$	4,327