Summary of Business and Significant Accounting Policies - Narrative (Detail)			3 Months Ended		6 Months Ended
	Jul. 31, 2020 USD ($) investment	Jan. 31, 2020 USD ($) investment	Jul. 31, 2020 USD ($) investment	Jul. 31, 2019 USD ($)	Jul. 31, 2020 USD ($) segment investment	Jul. 31, 2019 USD ($)
Summary of Business and Significant Accounting Policies [Line Items]
Number of operating segments | segment					1
Number of publicly traded investments | investment	1	1	1		1
Percent of total strategic investments, publicly traded	30.00%		30.00%		30.00%
Number of investments held | investment	3	5	3		3
Percent of total strategic investments, privately held		5.00%
Percent of total strategic investments		5.00%
Number of privately held investments | investment		4
Capitalized contract cost, amortization term (in years)	4 years		4 years		4 years
Capitalized contract cost, renewals and success fees, amortization term (in years)					2 years
Costs capitalized to obtain revenue contracts, net			$ 455,000,000	$ 173,000,000	$ 480,000,000	$ 297,000,000
Amortization of costs capitalized to obtain revenue contracts, net			250,000,000	217,000,000	497,000,000	426,000,000
Costs capitalized to obtain revenue contracts, net	$ 2,300,000,000	$ 2,300,000,000	2,300,000,000		2,300,000,000
Impairments of costs to obtain revenue contracts			$ 0	$ 0	0	0
Impairments of capitalized software and long-lived assets					0	0
Impairment of intangible assets					0	0
Impairment of goodwill					$ 0	$ 0
Offering period					12 months
Discount for ESPP					15.00%
Purchase period					6 months
Percentage of tax benefit likely to be realized upon settlement (greater than 50%)					50.00%
Stock options and restricted stock
Summary of Business and Significant Accounting Policies [Line Items]
Vesting period					4 years
Performance shares
Summary of Business and Significant Accounting Policies [Line Items]
Vesting period					3 years
Restricted Stock
Summary of Business and Significant Accounting Policies [Line Items]
Award requisite service period					4 years
Non-US | Assets | Geographic Concentration Risk
Summary of Business and Significant Accounting Policies [Line Items]
Concentration risk percentage	15.00%	12.00%
Untied States | Assets | Geographic Concentration Risk
Summary of Business and Significant Accounting Policies [Line Items]
Concentration risk percentage	83.00%	87.00%
Internal-use software | Minimum
Summary of Business and Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives					3 years
Internal-use software | Maximum
Summary of Business and Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives					5 years