Information by Geographic Area Revenues (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Service revenues	$ 17,887	$ 15,409	$ 34,136	$ 30,799
Subscriber equipment revenues	6,107	4,426	10,394	8,369
Total revenue	23,994	19,835	44,530	39,168
United States
Segment Reporting Information [Line Items]
Service revenues	11,853	11,048	22,733	22,225
Subscriber equipment revenues	3,515	2,828	5,829	5,068
Canada
Segment Reporting Information [Line Items]
Service revenues	3,636	3,035	6,869	5,677
Subscriber equipment revenues	1,487	978	2,769	1,763
Europe
Segment Reporting Information [Line Items]
Service revenues	1,401	771	2,752	1,551
Subscriber equipment revenues	555	401	1,087	900
Central and South America
Segment Reporting Information [Line Items]
Service revenues	783	633	1,447	1,293
Subscriber equipment revenues	335	206	493	534
Others
Segment Reporting Information [Line Items]
Service revenues	214	(78)	335	53
Subscriber equipment revenues	$ 215	$ 13	$ 216	$ 104