Derivative Instruments (Additional Information) (Details) $ in Millions	6 Months Ended
	Jan. 27, 2018 USD ($) derivative	Jul. 29, 2017 derivative
Derivative [Line Items]
Net derivative gains or losses to be reclassified from AOCI into earnings in next twelve months | $	$ 56
Fixed Income Securities
Derivative [Line Items]
Number of interest rate derivatives held (derivative) | derivative	0	0
Derivatives designated as cash flow hedging instruments:
Derivative [Line Items]
Foreign currency cash flow hedges maturity period, maximum, months	24 months