Pension And Postretirement Benefits (Schedule Of Components of Benefit Expense) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2021	Jan. 26, 2020	Jan. 31, 2021	Jan. 26, 2020
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), (Gain) Loss Due to Settlement	$ (30)	$ (11)	$ (34)	$ (11)
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	4	5	9	10
Defined Benefit Plan, Interest Cost	10	17	20	34
Expected return on plan assets	(30)	(34)	(61)	(69)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), (Gain) Loss Due to Settlement	(30)	(11)	(34)	(11)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(46)	(23)	(66)	(36)
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	0	0	0	0
Defined Benefit Plan, Interest Cost	1	1	2	3
Expected return on plan assets	0	0	0	0
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(1)	(7)	(2)	(14)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), (Gain) Loss Due to Settlement	0	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 0	$ (6)	$ 0	$ (11)