Pension And Postretirement Benefits Pension and Postretirement Benefits (Schedule of Investments Valued Using Net Asset Value) (Details) - Pension Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Aug. 02, 2020	Jul. 28, 2019	Jul. 29, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 2,120	$ 2,153	$ 2,154
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	0	0
Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	568	644
Short-term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	42	78
Short-term Investments [Member] | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 22	23
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	1 day
Equity Funds [Member] | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 262	319
Equity Funds [Member] | Fair Value Measured at Net Asset Value Per Share | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	1
Equity Funds [Member] | Fair Value Measured at Net Asset Value Per Share | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	60 days
Fixed Income Funds [Member] | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 139	35
Fixed Income Funds [Member] | Fair Value Measured at Net Asset Value Per Share | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	2
Fixed Income Funds [Member] | Fair Value Measured at Net Asset Value Per Share | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	50 days
Blended Funds [Member] | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 0	84
Blended Funds [Member] | Fair Value Measured at Net Asset Value Per Share | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	1
Blended Funds [Member] | Fair Value Measured at Net Asset Value Per Share | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	20 days
Real Estate Funds [Member] | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 84	107
Real Estate Funds [Member] | Fair Value Measured at Net Asset Value Per Share | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	45
Real Estate Funds [Member] | Fair Value Measured at Net Asset Value Per Share | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	90 days
Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 31	32
Hedge Funds [Member] | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 61	$ 76
Hedge Funds [Member] | Fair Value Measured at Net Asset Value Per Share | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	5
Hedge Funds [Member] | Fair Value Measured at Net Asset Value Per Share | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	30 days
Real Estate Funds with a Redemption Queue [Member] | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 35