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. 31, 2016		Aug. 02, 2015
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure		$ 691		$ 805
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments		0		28
Short-term Investments [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure		$ 20		28
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 Investments, Fair Value Disclosure		$ 309		375
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		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
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 Investments, Fair Value Disclosure		$ 31		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
Blended Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure		$ 79		79
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
Real Estate Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure		$ 108	[1]	117
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments		$ 0		3
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency		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		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
Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure		$ 144	[2]	175
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments		$ 0		$ 25
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
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		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]	$ 45

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

[2] Includes a fund valued at $45 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, 2016.