Immaterial Correction of Prior Period Financial Statements (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Total revenues	$ 1,944,312	$ 1,791,288	$ 2,013,942
Cost of Purchased Oil and Gas	1,546,987	1,397,530	1,638,777
Total operating costs and expenses	1,991,948	1,756,459	1,939,469
Operating income	(47,636)	34,829	74,473
Scenario, Actual [Member]
Total revenues		1,791,288
Cost of Purchased Oil and Gas		1,397,530
Total operating costs and expenses		1,756,459
Operating income		34,829
Classification of New Opportunity Processing [Member] | Scenario, Adjustment [Member]
Cost of Purchased Oil and Gas		135,400
Classification of New Opportunity Processing [Member] | Scenario, Previously Reported [Member]
Total revenues		1,655,851
Cost of Purchased Oil and Gas		1,262,093
Total operating costs and expenses		1,621,022
Operating income		$ 34,829