Discontinued Operations (Major Categories of Assets and Liabilities Reflected as Held for Sale) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable	$ 293,312	$ 522,672
Total current assets held for sale	32,113	38,340
Total current liabilities associated with assets held for sale	4,135	7,297
UK Refining And Marketing Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash	3,007	7,927
Accounts receivable	12,403	12,037
Other	16,703	18,376
Total current assets held for sale	32,113	38,340
Accounts payable	488	2,433
Accrued compensation and severance		2,179
Refinery decommissioning cost	3,647	2,685
Total current liabilities associated with assets held for sale	$ 4,135	$ 7,297