Summary of significant accounting policies - Segment and geographic information (Details) $ in Thousands	3 Months Ended
Mar. 31, 2020 USD ($) segment	Mar. 31, 2019 USD ($)
Primary revenue source
Number of reportable segment \| segment	1
Revenue	$ 59,886	$ 66,473
Military/multifamily
Primary revenue source
Revenue	22,707	25,897
DAS
Primary revenue source
Revenue	22,196	24,095
Wholesale-Wi-Fi
Primary revenue source
Revenue	9,743	11,020
Retail
Primary revenue source
Revenue	2,959	3,926
Advertising and other
Primary revenue source
Revenue	$ 2,281	$ 1,535

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

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