Financial Instruments, Fair Value Measurements and Credit Risk - Narrative (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Oct. 08, 2012	Jan. 20, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign exchange losses, Colombian peso to U.S. dollar	$ 60
Colombia [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Number of significant customers	2
Colombia [Member] | Geographic Concentration Risk [Member] | Sales Revenue, Segment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Concentration risk, percentage	95.00%	96.00%	98.00%
Brazil [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Number of significant customers	1
Block-Brazil [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Participating interest percentage oil and gas property, remaining percentage				30.00%	30.00%