Summary of significant accounting policies (Details 6) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) segment	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Primary revenue source
Number of reportable segments | segment									1
Revenue	$ 38,771	$ 37,186	$ 34,277	$ 29,392	$ 33,627	$ 30,822	$ 28,396	$ 26,452	$ 139,626	$ 119,297	$ 106,746
DAS
Primary revenue source
Revenue									46,455	38,259	32,681
Retail
Primary revenue source
Revenue									31,763	40,336	43,194
Wholesale - Wi-Fi
Primary revenue source
Revenue									21,923	15,209	17,261
Military
Primary revenue source
Revenue									19,898	4,486	1,260
Advertising and other
Primary revenue source
Revenue									$ 19,587	$ 21,007	$ 12,350