Pension And Postretirement Benefits (Amounts Recognized in Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Jul. 31, 2016	Aug. 02, 2015
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities	$ 14	$ 20
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	501	233
Defined Benefit Plan, Amounts Recognized in Balance Sheet	515	253
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities	28	30
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	285	362
Defined Benefit Plan, Amounts Recognized in Balance Sheet	313	392
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	$ 96	$ 4