Other Comprehensive Income (Loss) - Other Comprehensive Income (Loss) Amounts Reclassified to Income Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Comprehensive Income (Loss) Reclassified to Income Statement [Line Items]
Sales and other revenues	$ (11,183,643)	$ (17,486,578)	$ (17,714,666)
Cost of Goods and Services Sold	(9,158,805)	(13,918,384)	(13,940,782)
Operating expenses	(1,300,277)	(1,394,052)	(1,285,838)
Income tax expense (benefit)	(232,147)	299,152	347,243
Net of tax	(514,899)	872,352	1,177,224
Reclassification out of Accumulated Other Comprehensive Income
Other Comprehensive Income (Loss) Reclassified to Income Statement [Line Items]
Net of tax	1,013	17,354	(1,938)
Commodity contracts | Reclassification out of Accumulated Other Comprehensive Income
Other Comprehensive Income (Loss) Reclassified to Income Statement [Line Items]
Cost of Goods and Services Sold	(4,281)	(22,876)	0
Hedging instruments: | Reclassification out of Accumulated Other Comprehensive Income
Other Comprehensive Income (Loss) Reclassified to Income Statement [Line Items]
Before tax	(2,604)	19,713	(6,055)
Income tax expense (benefit)	(664)	5,027	(1,544)
Net of tax	(1,940)	14,686	(4,511)
Hedging instruments: | Commodity contracts | Reclassification out of Accumulated Other Comprehensive Income
Other Comprehensive Income (Loss) Reclassified to Income Statement [Line Items]
Sales and other revenues	(5,168)	(1,799)	(5,093)
Cost of Goods and Services Sold	4,281	22,876	0
Operating expenses	(1,717)	(1,364)	(962)
Other post-retirement benefit obligations: | Reclassification out of Accumulated Other Comprehensive Income | Pension obligations
Other Comprehensive Income (Loss) Reclassified to Income Statement [Line Items]
Income tax expense (benefit)	108	0	0
Net of tax	314	0	0
Other General Expense	422	0	0
Other post-retirement benefit obligations: | Reclassification out of Accumulated Other Comprehensive Income | Post-retirement healthcare obligations
Other Comprehensive Income (Loss) Reclassified to Income Statement [Line Items]
Income tax expense (benefit)	909	915	888
Net of tax	2,655	2,672	2,593
Other General Expense	3,564	3,587	3,481
Other post-retirement benefit obligations: | Reclassification out of Accumulated Other Comprehensive Income | Retirement restoration plan
Other Comprehensive Income (Loss) Reclassified to Income Statement [Line Items]
Income tax expense (benefit)	(6)	(2)	(7)
Net of tax	(16)	(4)	(20)
Other General Expense	$ (22)	$ (6)	$ (27)