Fair Value Measurements (Fair Value Measurement Of Assets And Liabilities) (Details) - USD ($) $ in Millions		Jul. 30, 2017	Jul. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		$ 60	$ 38
Total liabilities at fair value		156	179
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		6	2
Total liabilities at fair value		113	123
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		5	11
Total liabilities at fair value		43	56
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		49	25
Deferred Compensation Obligation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation obligation	[1]	112	119
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	[1]	112	119
Measured On Recurring Basis [Member] | Foreign Exchange Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	[2]	3	1
Total liabilities at fair value	[2]	21	11
Measured On Recurring Basis [Member] | Foreign Exchange Forward Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	[2]	3	1
Total liabilities at fair value	[2]	21	11
Measured On Recurring Basis [Member] | Commodity Derivative Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	[3]	6	3
Total liabilities at fair value	[3]	1	4
Measured On Recurring Basis [Member] | Commodity Derivative Contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	[3]	6	2
Total liabilities at fair value	[3]	1	4
Measured On Recurring Basis [Member] | Commodity Derivative Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	[3]	0	1
Measured On Recurring Basis [Member] | Deferred Compensation Derivative Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	[4]	1	1
Total liabilities at fair value	[4]	0	1
Measured On Recurring Basis [Member] | Deferred Compensation Derivative Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	[4]	1	1
Total liabilities at fair value	[4]	0	1
Measured On Recurring Basis [Member] | Investments Fair Value Accounting [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[5]	50	33
Measured On Recurring Basis [Member] | Investments Fair Value Accounting [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[5]	1	8
Measured On Recurring Basis [Member] | Investments Fair Value Accounting [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[5]	49	25
Measured On Recurring Basis [Member] | Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value	[6]	22	44
Measured On Recurring Basis [Member] | Interest Rate Contract [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value	[6]	$ 22	$ 44

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

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

[3] Based on quoted futures exchanges and on observable prices of futures and options transactions in the marketplace.

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

[5] Primarily represents investments in equity securities that are not readily marketable and are accounted for under the fair value option. The investments were funded by Acre. See Note 14 for additional information. Fair value is based on analyzing recent transactions and transactions of comparable companies, and the discounted cash flow method. In addition, allocation methods, including the option pricing method, are used in distributing fair value among various equity holders according to rights and preferences. Changes in the fair value of investments were not material in 2017

[6] Based on LIBOR swap rates.