Leases (Details) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Property Subject To Or Available For Operating Lease [Line Items] | |||
| Rent expense for office space | $ 2,508 | $ 2,804 | $ 2,899 |
| Logistics business | |||
| Property Subject To Or Available For Operating Lease [Line Items] | |||
| Charter hire expense | 1,307 | 2,468 | 1,286 |
| Future minimum revenue | 262,711 | ||
| Chartered-in vessels | |||
| Property Subject To Or Available For Operating Lease [Line Items] | |||
| Charter hire expense | $ 136,920 | $ 111,337 | $ 116,962 |