Major classes of assets and liabilities Refining (Details 2) - USD ($) $ in Thousands		Mar. 31, 2018		Dec. 31, 2017		Mar. 31, 2017
Current assets:
Total current assets held for sale		$ 458		$ 479		$ 7,290
Current liabilities:
Total current liabilities held for sale		11,726		11,993		2,394
Refining | Discontinued operations, held-for-sale or disposed of by sale
Current assets:
Income taxes receivable		1,858	[1]	1,778	[1]	11,756
Total current assets held for sale		1,858		1,778		11,756
Total assets held for sale		1,858		1,778		11,756
Current liabilities:
Accounts payable		0		0		16
Total current liabilities held for sale		0		0		16
Noncurrent liabilities:
Deferred income taxes (b)	[2]	37		37		55
Total noncurrent liabilities held for sale		37		37		55
Total liabilities held for sale		$ 37		$ 37		$ 71

[1] On the Company's Consolidated Balance Sheets, these amounts were reclassified to taxes payable and are reflected in current liabilities held for sale.

[2] On the Company's Consolidated Balance Sheets, these amounts were reclassified to deferred charges and other assets - deferred income taxes and are reflected in noncurrent assets held for sale.