Long-Term Obligations and Commitments - Summary of Senior Unsecured Debt (Details) $ in Millions	Jul. 31, 2020 USD ($)
Debt Instrument [Line Items]
Long-term Debt	$ 2,048
Senior Unsecured Notes \| The Notes
Debt Instrument [Line Items]
Total senior unsecured notes	2,000
Unamortized discount and debt issuance costs	(17)
Long-term Debt	1,983
Senior Unsecured Notes \| 0.650% Notes Due July 2023
Debt Instrument [Line Items]
Total senior unsecured notes	$ 500
Stated interest rate (in percent)	0.65%
Effective interest rate (in percent)	0.837%
Senior Unsecured Notes \| 0.950% Notes Due July 2025
Debt Instrument [Line Items]
Total senior unsecured notes	$ 500
Stated interest rate (in percent)	0.95%
Effective interest rate (in percent)	1.127%
Senior Unsecured Notes \| 1.350% notes due July 2027
Debt Instrument [Line Items]
Total senior unsecured notes	$ 500
Stated interest rate (in percent)	1.35%
Effective interest rate (in percent)	1.486%
Senior Unsecured Notes \| 1.650% notes due July 2030
Debt Instrument [Line Items]
Total senior unsecured notes	$ 500
Stated interest rate (in percent)	1.65%
Effective interest rate (in percent)	1.767%

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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