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. 30, 2017	Jul. 31, 2016
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure		$ 666	$ 691
Short-term Investments [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure		$ 31	$ 20
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency		Daily	Daily
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		1 day	1 day
Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure		$ 332	$ 309
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,	Daily,
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		2 days	1 day
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	Monthly
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		60 days	60 days
Fixed Income Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure		$ 30	$ 31
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency		Daily	Daily
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		1 day	1 day
Blended Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure		$ 86	$ 79
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency		Primarily Daily	Primarily Daily
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description			1 day
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 Investments, Fair Value Disclosure		$ 84	$ 108	[1]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency		Quarterly	Primarily 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	1 day
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	90 days
Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	$ 103	$ 144
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, Frequency			Monthly,
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		5 days	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, Frequency			Quarterly
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		30 days	65 days
Real Estate Funds with a Redemption Queue [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure	[1]		$ 34
Hedge Funds - Being Liquidated [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure	[2]	$ 2	$ 45

[1] Included real estate investments valued at $34 in 2016 for which a redemption queue was imposed by the investment manager increasing the redemption receipt period to up to 9 months after notice.

[2] Includes a fund valued at $2 in 2017 and $45 in 2016 which is being liquidated. Distributions from the fund will be received as the underlying investments are liquidated which is estimated to occur by December 31, 2017.