Summary of Business and Significant Accounting Policies - Narrative (Detail)	12 Months Ended
	Jan. 31, 2020 USD ($) segment investments	Jan. 31, 2019 USD ($) investments	Jan. 31, 2018 USD ($)	Feb. 01, 2019 USD ($)
Summary of Business and Significant Accounting Policies [Line Items]
Number of operating segments | segment	1
Allowance for doubtful accounts	$ 23,000,000	$ 22,000,000
Number of investments held | investments	5	5
Percent of total strategic investments	0.05	0.05
Number of publicly traded investments | investments	1	4
Number of privately held investments | investments	4	1
Capitalized contract cost, amortization term (in years)	4 years
Capitalized contract cost, renewals and success fees, amortization term (in years)	2 years
Costs capitalized to obtain revenue contracts, net	$ 1,130,000,000	$ 981,000,000	$ 1,156,000,000
Amortization of costs capitalized to obtain revenue contracts, net	876,000,000	737,000,000	592,000,000
Costs capitalized to obtain revenue contracts, net	2,300,000,000	2,000,000,000.0
Impairments of costs to obtain revenue contracts	0	0	0
Impairments of capitalized software and long-lived assets	0	0	0
Impairment of intangible assets	0	0	0
Impairment of goodwill	$ 0	0	0
Offering period	12 months
Discount for ESPP	15.00%
Purchase period	6 months
Advertising expense	$ 660,000,000	$ 482,000,000	$ 373,000,000
Percentage of tax benefit likely to be realized upon settlement (greater than 50%)	50.00%
Operating lease right-of-use assets	$ 3,040,000,000
Operating lease liabilities	$ 3,195,000,000
ASU 2016-02
Summary of Business and Significant Accounting Policies [Line Items]
Operating lease right-of-use assets				$ 2,900,000,000
Operating lease liabilities				$ 3,100,000,000
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	12.00%	14.00%
Untied States | Assets | Geographic Concentration Risk
Summary of Business and Significant Accounting Policies [Line Items]
Concentration risk percentage	87.00%	84.00%
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