Pension And Postretirement Benefits (Amounts Recognized in Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Jul. 29, 2018	Jul. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	$ 61	$ 8
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	61	8
Liability, Defined Benefit Plan, Current	14	14
Liability, Defined Benefit Plan, Noncurrent	150	261
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position	103	267
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax	2	0
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	0	0
Liability, Defined Benefit Plan, Current	29	29
Liability, Defined Benefit Plan, Noncurrent	206	247
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position	235	276
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax	$ (67)	$ (83)