Investments in unconsolidated companies - Summarized balance sheet for investments in unconsolidated companies (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Summarized financial data for OEH's unconsolidated companies
Current assets	$ 81,041	$ 96,247
Property, plant and equipment, net of accumulated depreciation	304,493	295,662
Other non-current assets	29,159	29,442
Non-current assets	333,652	325,104
Total assets	414,693	421,351
Current liabilities, including $21,476 and $21,021 current portion of third-party debt	92,372	89,785
Long-term debt	144,607	153,876
Other non-current liabilities	28,042	27,545
Non-current liabilities	172,649	181,421
Total shareholders’ equity	149,672	150,145
Total liabilities and shareholders’ equity	$ 414,693	$ 421,351