Fair Value Measurements (Fair Value Measurements At Reporting Date) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Assets:
Deferred receivables consideration	$ 446	$ 379
Fair Value, Recurring [Member]
Assets:
Inventories carried at market	4,704	4,547
Cash Equivalents	505	1,288
Debt Securities, Available-for-sale	5	13
Segregated investments	628	1,044
Deferred receivables consideration	446	379
Total Assets	6,907	7,907
Liabilities:
Inventory-related payables	729	597
Total Liabilities	1,471	1,358
Fair Value, Recurring [Member] | Commodity Contracts [Member]
Assets:
Derivative Asset	478	461
Liabilities:
Derivative Liability	574	589
Fair Value, Recurring [Member] | Foreign Exchange Contract [Member]
Assets:
Derivative Asset	138	175
Liabilities:
Derivative Liability	125	152
Fair Value, Recurring [Member] | Interest Rate Contracts [Member]
Assets:
Derivative Asset	3
Liabilities:
Derivative Liability	43	20
Fair Value, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Assets:
Inventories carried at market	0	0
Cash Equivalents	505	1,288
Debt Securities, Available-for-sale	5	12
Segregated investments	628	1,044
Deferred receivables consideration	0	0
Total Assets	1,138	2,344
Liabilities:
Inventory-related payables	0	0
Total Liabilities	0	0
Fair Value, 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, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Foreign Exchange Contract [Member]
Assets:
Derivative Asset	0	0
Liabilities:
Derivative Liability	0	0
Fair Value, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Interest Rate Contracts [Member]
Assets:
Derivative Asset	0
Liabilities:
Derivative Liability	0	0
Fair Value, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Inventories carried at market	3,227	3,032
Debt Securities, Available-for-sale	0	1
Segregated investments	0
Deferred receivables consideration	446	379
Total Assets	4,091	3,893
Liabilities:
Inventory-related payables	702	579
Total Liabilities	1,245	1,095
Fair Value, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Commodity Contracts [Member]
Assets:
Derivative Asset	277	306
Liabilities:
Derivative Liability	375	344
Fair Value, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Foreign Exchange Contract [Member]
Assets:
Derivative Asset	138	175
Liabilities:
Derivative Liability	125	152
Fair Value, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Interest Rate Contracts [Member]
Assets:
Derivative Asset	3
Liabilities:
Derivative Liability	43	20
Fair Value, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Inventories carried at market	1,477	1,515
Debt Securities, Available-for-sale	0	0
Deferred receivables consideration	0	0
Total Assets	1,678	1,670
Liabilities:
Inventory-related payables	27	18
Total Liabilities	226	263
Fair Value, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Commodity Contracts [Member]
Assets:
Derivative Asset	201	155
Liabilities:
Derivative Liability	199	245
Fair Value, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Foreign Exchange Contract [Member]
Assets:
Derivative Asset	0	0
Liabilities:
Derivative Liability	0	0
Fair Value, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Interest Rate Contracts [Member]
Assets:
Derivative Asset	0
Liabilities:
Derivative Liability	$ 0	$ 0