Discontinued Operations (Major Categories of Assets and Liabilities Reflected as Held for Sale) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable	$ 320,935	$ 357,099
Total current assets held for sale	25,485	27,070
Accounts payable	712,201	784,975
Total current liabilities associated with assets held for sale	2,816	2,776
UK Refining And Marketing Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash	16,340	4,126
Accounts receivable	9,145	22,944
Total current assets held for sale	25,485	27,070
Accounts payable	367	270
Refinery decommissioning cost	2,449	2,506
Total current liabilities associated with assets held for sale	$ 2,816	$ 2,776