Investment in Affiliate (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2014	Sep. 30, 2015	Dec. 31, 2014	Jan. 15, 2015
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Impairment			$ 355,650
Allowance recorded		$ 550
Petrodelta, S.A. [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Indirect ownership percentage		40.00%		51.00%
Allowance recorded	$ 12,200		$ 1,600