Pension And Postretirement Benefits (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 29, 2018	Apr. 30, 2017	Apr. 29, 2018	Apr. 30, 2017
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Cost of Providing Special and Contractual Termination Benefits	$ 0	$ 0	$ 2	$ 0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(11)	$ (9)	(32)	$ (25)
Change in Accounting Method [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ (4)		$ (12)