Fair Value Measurements (Fair Value Measurement Of Assets And Liabilities) (Details) - Measured On Recurring Basis [Member] - USD ($) $ in Millions		Jan. 31, 2021	Aug. 02, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value		$ 23	$ 15
Total liabilities at fair value		114	103
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value		12	6
Total liabilities at fair value		108	97
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value		11	7
Total liabilities at fair value		5	6
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value		0	2
Total liabilities at fair value		1	0
Foreign Exchange Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets at fair value	[1]	0	1
Derivatives liabilities at fair value	[1]	4	2
Foreign Exchange Forward Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets at fair value	[1]	0	1
Derivatives liabilities at fair value	[1]	4	2
Commodity Derivative Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets at fair value	[2]	17	7
Derivatives liabilities at fair value	[2]	2	9
Commodity Derivative Contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets at fair value	[2]	9	3
Derivatives liabilities at fair value	[2]	0	5
Commodity Derivative Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets at fair value	[2]	8	2
Derivatives liabilities at fair value	[2]	1	4
Commodity Derivative Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets at fair value	[2]	0	2
Derivatives liabilities at fair value	[2]	1	0
Deferred Compensation Derivative Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets at fair value	[3]	3	4
Deferred Compensation Derivative Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets at fair value	[3]	3	4
Deferred Compensation Investment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	[4]	3	3
Deferred Compensation Investment [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	[4]	3	3
Deferred Compensation Obligation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation obligation	[4]	108	92
Deferred Compensation Obligation [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation obligation	[4]	$ 108	$ 92

[1] Based on observable market transactions of spot currency rates and forward rates.

[2] Level 1 and 2 are based on quoted futures exchanges and on observable prices of futures and options transactions in the marketplace. Level 3 is based on unobservable inputs in which there is little or no market data, which requires management’s own assumptions within an internally developed model.

[3] Based on LIBOR and equity index swap rates.

[4] Based on the fair value of the participants’ investments.