Pension And Postretirement Benefits Pension And Postretirement Benefits (Schedule of Investments Valued Using Net Asset Value) (Details) - Pension Plan, Defined Benefit [Member] - USD ($) $ in Millions		12 Months Ended
		Jul. 29, 2018	Jul. 30, 2017
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investment, Fair Value Disclosure		$ 631	$ 666
Short-term Investments [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investment, Fair Value Disclosure		$ 21	31
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency		Daily
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		1 day
Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investment, Fair Value Disclosure		$ 310	332
Equity Funds [Member] | Minimum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency		Daily,
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		2 days
Equity Funds [Member] | Maximum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency		Monthly
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		60 days
Fixed Income Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investment, Fair Value Disclosure		$ 31	30
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency		Daily
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		1 day
Blended Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investment, Fair Value Disclosure		$ 85	86
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency		Primarily Daily
Blended Funds [Member] | Minimum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		1 day
Blended Funds [Member] | Maximum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		20 days
Real Estate Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investment, Fair Value Disclosure		$ 89	84
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency		Quarterly
Real Estate Funds [Member] | Minimum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		45 days
Real Estate Funds [Member] | Maximum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		90 days
Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investment, Fair Value Disclosure	[1]	$ 95	103
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency		Monthly
Hedge Funds [Member] | Minimum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		5 days
Hedge Funds [Member] | Maximum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		30 days
Hedge Funds - Being Liquidated [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investment, Fair Value Disclosure			$ 2

[1] Includes a fund valued at $2 in 2017 which was substantially liquidated in 2018.