Acquisitions - Narrative (Details) $ in Millions		3 Months Ended	12 Months Ended
	Nov. 23, 2020 USD ($) shares	Jan. 31, 2021 USD ($)	Jan. 31, 2021 USD ($) business_combination	Jan. 31, 2020 USD ($)	Jan. 31, 2019 USD ($) business_combination
Business Acquisition [Line Items]
Consideration transferred, equity interests			$ 37.9	$ 0.0	$ 44.8
Share-based compensation expense			$ 399.8	362.4	$ 249.5
Number of businesses acquired | business_combination			2		3
Goodwill		$ 193.0	$ 193.0
Goodwill		2,706.5	2,706.5	$ 2,445.0
Spacemaker
Business Acquisition [Line Items]
Consideration transferred	$ 252.0
Payments to acquire businesses	$ 214.1
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	147,264
Consideration transferred, equity interests	$ 37.9
Business Combination, Consideration Transferred, Other	231.1
Business Combination, Contingent Consideration, Asset	$ 18.9
Share-based compensation expense		2.0
Shares issued in period (in shares) | shares	73,632
Vesting period	3 years
Goodwill		189.4	189.4
Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Consideration transferred			45.4
Goodwill		$ 31.4	$ 31.4
Assemble Systems Inc
Business Acquisition [Line Items]
Consideration transferred					$ 1,120.0
Payments to acquire businesses					1,060.0
Consideration transferred, equity interests					44.8
Consideration					10.3
Equity interest prior to acquisition					10.6
Finite-lived intangibles					261.4
Goodwill					$ 868.0