Summary of significant accounting policies - Principles of consolidation (Details) |
Sep. 30, 2018 |
|---|---|
| Chicago Concourse Development Group, LLC | |
| Principles of consolidation | |
| Percentage of ownership in subsidiaries | 70.00% |
| Boingo Holding Participacoes Ltda. | |
| Principles of consolidation | |
| Percentage of ownership in subsidiaries | 75.00% |