Short-term Borrowings and Long-term Debt (Schedule of Short-term Debt) (Details) CAD in Millions, $ in Millions		Jul. 31, 2016 USD ($)	Jul. 31, 2016 CAD	Aug. 02, 2015 USD ($)
Short-term Debt [Line Items]
Commercial Paper		$ 770		$ 1,532
Notes Payable, Current		400		0
Capital Lease Obligations, Current		2		1
Other Short-term Borrowings	[1]	(1)		0
Debt, Current		1,219		1,543
Variable Interest Rate [Member]
Short-term Debt [Line Items]
Short-term Bank Loans and Notes Payable		6		1
Fixed Interest Rate [Member]
Short-term Debt [Line Items]
Short-term Bank Loans and Notes Payable		0		9
Foreign Line of Credit [Member] | Variable Interest Rate [Member]
Short-term Debt [Line Items]
Line of Credit, Current		$ 42	CAD 55	$ 0

[1] Includes unamortized net discount/premium on debt issuances and debt issuance costs