|
Summary of significant accounting policies (Details 5) (USD $)
In Thousands, unless otherwise specified |
12 Months Ended | |||
|---|---|---|---|---|
|
Dec. 31, 2014
|
Dec. 31, 2013
|
Dec. 31, 2012
|
Dec. 31, 2009
|
|
| Non-controlling interests | ||||
| Non-controlling owners capital account amount | 1,028 | $ 865 | ||
| Distributions to non-controlling interest holders | 623 | 608 | 678 | |
| Concourse Communications Detroit, LLC | ||||
| Non-controlling interests | ||||
| Initial term of Detroit Operating Agreement | 7 years | |||
| Optional extension period of Detroit Operating Agreement | 4 years | |||
| Non-controlling owners capital account amount | 0 | |||
| Distributions to non-controlling interest holders | 48 | 121 | ||
| Chicago Concourse Development Group LLC | ||||
| Non-controlling interests | ||||
| Percentage of net profits less capital expenditures of the preceding year allocated to non-controlling interest holders | 30.00% | |||
| Distributions to non-controlling interest holders | 623 | 560 | 557 | |
| Boingo Holding Participacoes Ltda | ||||
| Non-controlling interests | ||||
| Distributions to non-controlling interest holders | 0 | $ 0 | ||