Income taxes - Operating losses (Details) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Net operating loss carryforwards | |||
| Foreign loss before income taxes | $ 856 | $ 1,381 | $ 1,251 |
| United Kingdom | |||
| Net operating loss carryforwards | |||
| Foreign subsidiary deferred tax asset | 1,660 | ||
| Brazil | |||
| Net operating loss carryforwards | |||
| Foreign subsidiary deferred tax asset | 466 | ||
| Federal | |||
| Net operating loss carryforwards | |||
| The amount of gross unrealized net operating loss carryforwards | 55,780 | 55,278 | |
| State | |||
| Net operating loss carryforwards | |||
| The amount of gross unrealized net operating loss carryforwards | 56,006 | 68,614 | |
| Foreign | |||
| Net operating loss carryforwards | |||
| The amount of gross unrealized net operating loss carryforwards | $ 9,672 | $ 9,042 | |