Income Taxes - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Operating Loss Carryforwards [Line Items]
Reduction of income taxes payable				$ 59
Federal statutory income tax rate		26.90%
Provisional charge related to re-measurement of certain deferred tax balances	$ (1)	$ 43
Capital loss on subsidiary reorganization	35	35	$ 0	0
Excess tax benefits related to stock-based compensation		100	72
Discrete tax benefit due to changes in tax law				12
Total net deferred tax assets, net of valuation allowance	164	164	275
Valuation allowance	93	93	64
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Excess tax benefits related to stock-based compensation		6	3
Operating loss carryforwards	93	93
Total net deferred tax assets, net of valuation allowance	6	6
Valuation allowance	5	5
Domestic Country
Operating Loss Carryforwards [Line Items]
Excess tax benefits related to stock-based compensation		(94)	$ (69)	0
Operating loss carryforwards	16	16
Foreign Tax Authority | Inland Revenue, Singapore (IRAS)
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	84	84
Foreign Tax Authority | Secretariat of the Federal Revenue Bureau of Brazil
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	23	23
Capital Loss Carryforward | State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, valuation allowance				2
Research Tax Credit Carryforward | State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Deferred tax assets, tax credit carryforwards	$ 100	$ 100
Demandforce, QuickBase, and Quicken
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit) from discontinued operations				$ 179