Revenue, Deferred Revenue And Deferred Commissions (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) revenue_component	Jun. 30, 2017 USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 40,628	$ 42,325	$ 83,742	$ 83,769
Deferred revenue recognized from previous period			16,500
Wireless products and services
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	23,658	25,639	47,927	51,499
Subscription
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	441	623	861	1,167
Software licenses
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	1,552	1,641	5,508	2,812
Professional services
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	4,363	3,650	8,433	7,003
Hardware
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 1,107	1,127	$ 2,132	2,100
Maintenance
Revenues from External Customers and Long-Lived Assets [Line Items]
Typical duration of revenue recognition	1 year		1 year
Total revenue	$ 9,507	9,645	$ 18,881	19,188
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	39,109	40,869	81,044	81,374
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 1,519	$ 1,456	$ 2,698	$ 2,395
Wireless
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue primary component | revenue_component			2
Software
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue primary component | revenue_component			2