Debt instruments (Details) - USD ($) $ in Thousands |
Dec. 31, 2015 |
Dec. 31, 2014 |
|---|---|---|
| Debt Instrument [Line Items] | ||
| Debt Instrument, Principal Value | $ 90,500 | $ 104,118 |
| Subordinated debt, at fair value | 39,898 | 40,659 |
| LROC preferred units due 2015, Fair Value | 0 | 13,618 |
| Long-term Debt | 39,898 | 54,277 |
| Long-term Debt [Member] | ||
| Debt Instrument [Line Items] | ||
| Debt Instrument, Principal Value | 0 | 13,618 |
| Subordinated Debt [Member] | ||
| Debt Instrument [Line Items] | ||
| Debt Instrument, Principal Value | $ 90,500 | $ 90,500 |