Derivative Instruments (Effect of Derivative Instruments Designated as Fair Value Hedges and Underlying Hedged Items on Consolidated Statements of Operations) (Details) - Derivatives Designated as Fair Value Hedging Instruments - USD ($) $ in Millions	3 Months Ended
	Oct. 27, 2018	Oct. 28, 2017
Hedge Underlying Gain Loss [Line Items]
GAINS (LOSSES) ON DERIVATIVE INSTRUMENTS	$ (9)	$ (60)
GAINS (LOSSES) RELATED TO HEDGED ITEMS	9	60
Interest rate derivatives | Interest expense
Hedge Underlying Gain Loss [Line Items]
GAINS (LOSSES) ON DERIVATIVE INSTRUMENTS	(9)	(46)
GAINS (LOSSES) RELATED TO HEDGED ITEMS	9	46
Equity derivatives | Other income (loss), net
Hedge Underlying Gain Loss [Line Items]
GAINS (LOSSES) ON DERIVATIVE INSTRUMENTS	0	(14)
GAINS (LOSSES) RELATED TO HEDGED ITEMS	$ 0	$ 14