Revenues (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) revenue_component	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 43,114	$ 41,444
Deferred revenue	31,600		$ 32,500
Deferred revenue recognized	9,900
Wireless products and services
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	24,269	25,860
Subscription
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	420	543
Software licenses
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	3,956	1,171
Professional services
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	4,071	3,354
Hardware
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 1,024	973
Maintenance
Revenues from External Customers and Long-Lived Assets [Line Items]
Typical duration of revenue recognition	1 year
Revenue	$ 9,374	9,543
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	41,935	40,506
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	1,179	$ 938
Restatement Adjustment | Accounting Standards Update 2014-09
Revenues from External Customers and Long-Lived Assets [Line Items]
Deferred revenue	$ (4,200)		$ (4,200)
Wireless Operations
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue primary component | revenue_component	2
Software Operations
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue primary component | revenue_component	2