Fair Value Measurements (Fair Value Measurements At Reporting Date) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Assets:
Derivative Asset	$ 634	$ 449
Deferred receivables consideration	399	307
Liabilities:
Derivative Liability	847	464
Fair Value, Measurements, Recurring [Member]
Assets:
Inventories carried at market	5,392	4,886
Cash Equivalents, at Carrying Value	443	352
Available-for-sale Securities, Fair Value Disclosure	90	92
Restricted Investments, at Fair Value	2,077	1,733
Deferred receivables consideration	399	307
Total Assets	9,035	7,819
Liabilities:
Inventory-related payables	1,177	719
Total Liabilities	2,024	1,183
Fair Value, Measurements, Recurring [Member] | Commodity Contracts [Member]
Assets:
Derivative Asset	587	386
Liabilities:
Derivative Liability	740	371
Fair Value, Measurements, Recurring [Member] | Foreign Exchange Contracts [Member]
Assets:
Derivative Asset	47	63
Liabilities:
Derivative Liability	106	92
Fair Value, Measurements, Recurring [Member] | Interest Rate Contracts [Member]
Liabilities:
Derivative Liability	1	1
Fair Value, Measurements, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Assets:
Inventories carried at market	0	0
Cash Equivalents, at Carrying Value	443	352
Available-for-sale Securities, Fair Value Disclosure	89	91
Restricted Investments, at Fair Value	2,077	1,733
Deferred receivables consideration	0	0
Total Assets	2,609	2,176
Liabilities:
Inventory-related payables	0	0
Total Liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Commodity Contracts [Member]
Assets:
Derivative Asset	0	0
Liabilities:
Derivative Liability	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Foreign Exchange Contracts [Member]
Assets:
Derivative Asset	0	0
Liabilities:
Derivative Liability	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Interest Rate Contracts [Member]
Liabilities:
Derivative Liability	0	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Inventories carried at market	3,563	3,400
Cash Equivalents, at Carrying Value	0	0
Available-for-sale Securities, Fair Value Disclosure	1	1
Restricted Investments, at Fair Value	0	0
Deferred receivables consideration	399	307
Total Assets	4,481	4,046
Liabilities:
Inventory-related payables	1,102	680
Total Liabilities	1,658	1,041
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Commodity Contracts [Member]
Assets:
Derivative Asset	471	275
Liabilities:
Derivative Liability	449	268
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Foreign Exchange Contracts [Member]
Assets:
Derivative Asset	47	63
Liabilities:
Derivative Liability	106	92
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Interest Rate Contracts [Member]
Liabilities:
Derivative Liability	1	1
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Inventories carried at market	1,829	1,486
Cash Equivalents, at Carrying Value	0	0
Available-for-sale Securities, Fair Value Disclosure	0	0
Restricted Investments, at Fair Value	0	0
Deferred receivables consideration	0	0
Total Assets	1,945	1,597
Liabilities:
Inventory-related payables	75	39
Total Liabilities	366	142
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Commodity Contracts [Member]
Assets:
Derivative Asset	116	111
Liabilities:
Derivative Liability	291	103
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Foreign Exchange Contracts [Member]
Assets:
Derivative Asset	0	0
Liabilities:
Derivative Liability	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Interest Rate Contracts [Member]
Liabilities:
Derivative Liability	$ 0	$ 0