Leases (Details) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Property Subject To Or Available For Operating Lease [Line Items] | |||
| Rent expense for office space | $ 2,748 | $ 2,508 | $ 2,804 |
| Expansion of its dry port | |||
| Property Subject To Or Available For Operating Lease [Line Items] | |||
| Future minimum revenue | $ 44,200 | ||
| Lease term | P20Y | ||
| Construction of river and estuary tanker | |||
| Property Subject To Or Available For Operating Lease [Line Items] | |||
| Future minimum revenue | $ 41,640 | ||
| Lease term | P5Y | ||
| Logistics business | |||
| Property Subject To Or Available For Operating Lease [Line Items] | |||
| Charter hire expense | $ 1,521 | 1,307 | 2,468 |
| Future minimum revenue | 1,067,598 | ||
| Chartered-in vessels | |||
| Property Subject To Or Available For Operating Lease [Line Items] | |||
| Charter hire expense | $ 84,114 | $ 134,364 | $ 111,386 |