Leases - Narrative (Details) $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2020 USD ($)	Jul. 31, 2021 USD ($) optionsToExtend	Jul. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease terms		10 years
Number of options to extend | optionsToExtend		1
Option to extend operating leases		10 years
Operating sublease terms		4 years
Reduction of right-of-use asset	$ 61
Reduction of lease liability	$ 61
Sublease rent expense			$ 42
Sublease rental income			$ 24
Leases not yet commenced		$ 43
Minimum
Lessee, Lease, Description [Line Items]
Number of sublease renewal options | optionsToExtend		1
Terms for leases not yet commenced		1 year
Maximum
Lessee, Lease, Description [Line Items]
Term of sublease renewal options (up to)		5 years
Terms for leases not yet commenced		11 years