Discontinued Operations (Major Categories of Assets and Liabilities Reflected as Held for Sale) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable	$ 523,368	$ 873,277	[1]
Total current assets held for sale	342,645	376,130	[1]
Property, plant and equipment, net	12,480,861	13,331,047	[1]
Other	56,320	62,582	[1]
Total non-current assets held for sale	35,468	50,960	[1]
Total current liabilities associated with assets held for sale	148,885	151,548	[1]
Deferred income taxes payable	936,979	1,193,864	[1]
Deferred credits and other liabilities	421,126	441,048	[1]
Total non-current liabilities associated with assets held for sale	5,225	8,310	[1]
UK Refining And Marketing Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash	135,806	200,512
Accounts receivable	127,341	97,568
Inventories	38,053	42,161
Other	41,445	35,889
Total current assets held for sale	342,645	376,130
Property, plant and equipment, net	35,453	50,947
Other	15	13
Total non-current assets held for sale	35,468	50,960
Accounts payable	48,228	59,023
Other accrued taxes payable	78,428	40,653
Accrued compensation and severance	10,276	30,872
Refinery decommissioning cost	11,953	21,000
Total current liabilities associated with assets held for sale	148,885	151,548
Deferred income taxes payable	1,002	3,873
Deferred credits and other liabilities	4,223	4,437
Total non-current liabilities associated with assets held for sale	$ 5,225	$ 8,310

[1] Reclassified to conform to current presentation.