Fair Value Measurements (Fair Value Measurement Of Assets And Liabilities) (Details) - USD ($) $ in Millions		Apr. 29, 2018	Jul. 30, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		$ 86	$ 60
Total liabilities at fair value		110	156
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		13	6
Total liabilities at fair value		107	113
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		4	5
Total liabilities at fair value		3	43
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		69	49
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	[1]	3	3
Total liabilities at fair value	[1]	1	21
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	[1]	3	3
Total liabilities at fair value	[1]	1	21
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	[2]	8	6
Total liabilities at fair value	[2]	3	1
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	[2]	7	6
Total liabilities at fair value	[2]	2	1
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	[2]	1	0
Total liabilities at fair value	[2]	1	0
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	[3]	0	1
Total liabilities at fair value	[3]	1	0
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	[3]	0	1
Total liabilities at fair value	[3]	1	0
Measured On Recurring Basis [Member] | Deferred Compensation Investment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	[4]	6	0
Measured On Recurring Basis [Member] | Deferred Compensation Investment [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	[4]	6	0
Measured On Recurring Basis [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	[5]	69	50
Measured On Recurring Basis [Member] | Equity Securities [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]	0	1
Measured On Recurring Basis [Member] | Equity Securities [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]	69	49
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]	0	22
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]	0	22
Measured On Recurring Basis [Member] | Deferred Compensation Obligation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation obligation	[4]	105	112
Measured On Recurring Basis [Member] | 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]	$ 105	$ 112

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

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

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

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

[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 2018 or 2017.

[6] Based on LIBOR swap rates.