Financial Instruments - Narrative (Details) - USD ($)	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
Derivatives, Fair Value [Line Items]
Securities in continuous unrealized loss position for greater than twelve months	$ 0	$ 0
Allowance for credit loss	0
Securities, writeoff	0
Available-for-sale securities gross gains (losses)	600,000	0	$ (1,300,000)
Proceeds from sale and maturity of marketable securities	17,000,000.0	27,400,000	$ 531,000,000.0
Non-marketable equity securities investments without readily determinable fair value	134,100,000	122,500,000
Derivative, notional amount	1,140,000,000	981,300,000
Net loss expected to be recognized into earnings	24,100,000
Foreign Exchange Contracts
Derivatives, Fair Value [Line Items]
Derivative, notional amount	$ 434,500,000	$ 736,200,000