Pension And Postretirement Benefits (Schedule Of Components of Benefit Expense) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 30, 2017	May 01, 2016	Apr. 30, 2017	May 01, 2016
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Defined Benefit Plan, Service Cost	$ 6	$ 6	$ 19	$ 20
Defined Benefit Plan, Interest Cost	21	24	64	74
Expected return on plan assets	(36)	(36)	(108)	(111)
Amortization of Prior Service Cost (Credit)	0	(1)	0	(1)
Defined Benefit Plans Recognized Actuarial Gains (Losses)	0	(61)	0	(173)
Defined Benefit Plan, Net Periodic Benefit Cost	(9)	54	(25)	155
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Defined Benefit Plan, Service Cost	0	0	1	1
Defined Benefit Plan, Interest Cost	2	4	7	12
Expected return on plan assets	0	0	0	0
Amortization of Prior Service Cost (Credit)	(5)	0	(18)	(1)
Defined Benefit Plans Recognized Actuarial Gains (Losses)	0	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost	$ (3)	$ 4	$ (10)	$ 12