Other Comprehensive Income (Loss) (Accumulated Other Comprehensive Loss In Equity) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales and other revenues	$ 4,471,236		$ 3,458,864	$ 8,599,663	$ 6,539,347
Operating expenses	296,215	[1]	316,261	616,503	623,987
Interest expense	(32,324)		(29,645)	(65,047)	(56,803)
Income before income taxes	480,360		106,069	854,259	51,498
Income tax expense (benefit)	117,447		31,996	202,484	15,207
Net of tax and noncontrolling interest	345,507		57,767	613,598	12,299
Other comprehensive income (loss), net of tax	(7,948)		10,594	(17,956)	8,156
Foreign currency translation adjustment	(4,116)			(4,116)		$ 14,377
Unrealized loss on pension obligation	(692)			(692)		(654)
Unrealized gain on post-retirement benefit obligations	20,711			20,711		16,939
Unrealized loss on hedging instruments, net of noncontrolling interest	(3,990)			(3,990)		(793)
Accumulated other comprehensive income	11,913			11,913		$ 29,869
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other comprehensive income (loss), net of tax	(4,171)		56	(3,283)	(335)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	(5,598)		157	(4,407)	(474)
Income tax expense (benefit)	(1,427)		36	(1,124)	(212)
Net income	(4,171)		121	(3,283)	(262)
Noncontrolling interest	0		(65)	0	(73)
Net of tax and noncontrolling interest	(4,171)		56	(3,283)	(335)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Commodity Contract [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales and other revenues	(5,317)		4,476	(3,671)	8,426
Cost of Goods Sold				0	(299)
Operating expenses	(281)		(4,421)	(736)	(8,716)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Interest Rate Swap [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 0		$ 102	$ 0	$ 115

[1] (1) During the three months ended June 30, 2018, we recognized an adjustment in our Lubricants and Specialty Products segment to correct an expense misclassification related to the three months ended March 31, 2018, whereby $24 million of inventory transportation costs were classified as operating expenses, which should have been included in cost of products sold.