Pension And Postretirement Benefits (Amounts Recognized in Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Jul. 30, 2017	Jul. 31, 2016
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits, Noncurrent	$ 8	$ 0
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities	14	14
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	261	501
Defined Benefit Plan, Amounts Recognized in Balance Sheet	267	515
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits, Noncurrent	0	0
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities	29	28
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	247	285
Defined Benefit Plan, Amounts Recognized in Balance Sheet	276	313
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	$ 83	$ 96