Summary of significant accounting policies- Revenue by primary source (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) segment	Sep. 30, 2016 USD ($)
Primary revenue source
Number of reportable segments | segment			1
Revenue	$ 53,655	$ 40,796	$ 147,021	$ 114,370
DAS
Primary revenue source
Revenue	21,755	15,959	56,563	40,957
Military
Primary revenue source
Revenue	13,946	10,137	40,029	28,969
Wholesale-Wi-Fi
Primary revenue source
Revenue	8,307	5,888	22,438	16,031
Retail
Primary revenue source
Revenue	6,234	6,619	19,007	20,100
Advertising and other
Primary revenue source
Revenue	$ 3,413	$ 2,193	$ 8,984	$ 8,313