Investments in unconsolidated companies - Summarized financial data for investments in unconsolidated companies (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013
Summarized financial data for OEH's unconsolidated companies
Current assets	$ 61,766				$ 64,145
Property, plant and equipment, net	342,595				342,731
Other assets	24,014				24,142
Non-current assets	366,609				366,873
Total assets	428,375				431,018
Current liabilities	153,803				154,213
Long-term debt	32,843				37,043
Other liabilities	129,284				127,002
Non-current liabilities	162,127				164,045
Total shareholders’ equity	112,445				112,760
Total liabilities and shareholders’ equity	428,375				431,018
Revenue	34,715		35,160
Gross profit	18,481	[1]	19,262	[1]
Net earnings	$ (352)	[2]	$ (994)	[2]

[1] Gross profit is defined as revenues less cost of services of the unconsolidated companies.

[2] There were no discontinued operations, extraordinary items or cumulative effects of a change in an accounting principle in the unconsolidated companies.