Financial Instruments - Cost and Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Jan. 31, 2022	Jan. 31, 2021
Cash equivalents:
Amortized Cost	$ 1,528.4	$ 1,772.2
Short-term trading securities
Derivative contract assets, amortized cost	0.1	0.1
Derivative contract assets, gross unrealized gains	0.4	0.4
Derivative contract assets, gross unrealized losses	(0.4)	(0.3)
Derivative contract assets, fair value	0.1	0.2
Amortized cost	779.4	796.3
Gross unrealized gains	37.4	26.7
Gross unrealized losses	(11.7)	(18.2)
Fair value	805.1	804.8
Foreign currency contracts
Short-term trading securities
Derivative contract assets, amortized cost	1.1	0.4
Derivative contract assets, gross unrealized gains	17.1	9.8
Derivative contract assets, gross unrealized losses	(0.2)	(0.4)
Derivative contract assets, fair value	18.0	9.8
Derivative contract liabilities, amortized cost	0.0	0.0
Derivative contract liabilities, gross unrealized gains	0.0	0.0
Derivative contract liabilities, Gross unrealized losses	(10.7)	(17.5)
Derivative contract liabilities, fair value	(10.7)	(17.5)
Level 1
Short-term trading securities
Derivative contract assets, fair value	0.0	0.0
Fair value	413.9	771.9
Level 1 | Foreign currency contracts
Short-term trading securities
Derivative contract assets, fair value	0.0	0.0
Derivative contract liabilities, fair value	0.0	0.0
Level 2
Short-term trading securities
Derivative contract assets, fair value	0.0	0.0
Fair value	391.1	32.7
Level 2 | Foreign currency contracts
Short-term trading securities
Derivative contract assets, fair value	18.0	9.8
Derivative contract liabilities, fair value	(10.7)	(17.5)
Level 3
Short-term trading securities
Derivative contract assets, fair value	0.1	0.2
Fair value	0.1	0.2
Level 3 | Foreign currency contracts
Short-term trading securities
Derivative contract assets, fair value
Derivative contract liabilities, fair value	0.0	0.0
Money market funds
Cash equivalents:
Amortized Cost	302.3	686.9
Fair Value	302.3	686.9
Money market funds | Level 1
Cash equivalents:
Fair Value	302.3	686.9
Money market funds | Level 2
Cash equivalents:
Fair Value	0.0	0.0
Money market funds | Level 3
Cash equivalents:
Fair Value	0.0	0.0
Commercial paper
Cash equivalents:
Amortized Cost	54.7	36.0
Fair Value	54.7	36.0
Commercial paper | Short-term
Marketable securities:
Amortized Cost	102.9
Gross Unrealized Gains	0.0
Gross Unrealized Losses	0.0
Fair Value	102.9
Commercial paper | Level 1
Cash equivalents:
Fair Value	0.0	0.0
Commercial paper | Level 1 | Short-term
Marketable securities:
Fair Value	0.0
Commercial paper | Level 2
Cash equivalents:
Fair Value	54.7	36.0
Commercial paper | Level 2 | Short-term
Marketable securities:
Fair Value	102.9
Commercial paper | Level 3
Cash equivalents:
Fair Value	0.0	0.0
Commercial paper | Level 3 | Short-term
Marketable securities:
Fair Value	0.0
U.S. government securities
Cash equivalents:
Amortized Cost	25.0
Fair Value	25.0
U.S. government securities | Short-term
Marketable securities:
Amortized Cost	12.5
Gross Unrealized Gains	0.0
Gross Unrealized Losses	0.0
Fair Value	12.5
U.S. government securities | Level 1
Cash equivalents:
Fair Value	0.0
U.S. government securities | Level 1 | Short-term
Marketable securities:
Fair Value	0.0
U.S. government securities | Level 2
Cash equivalents:
Fair Value	25.0
U.S. government securities | Level 2 | Short-term
Marketable securities:
Fair Value	12.5
U.S. government securities | Level 3
Cash equivalents:
Fair Value	0.0
U.S. government securities | Level 3 | Short-term
Marketable securities:
Fair Value	0.0
Custody cash deposit
Cash equivalents:
Amortized Cost	17.8	4.4
Fair Value	17.8	4.4
Custody cash deposit | Level 1
Cash equivalents:
Fair Value	17.8	4.0
Custody cash deposit | Level 2
Cash equivalents:
Fair Value	0.0	0.4
Custody cash deposit | Level 3
Cash equivalents:
Fair Value	0.0	0.0
Corporate debt securities
Cash equivalents:
Amortized Cost	17.6
Fair Value	17.6
Corporate debt securities | Short-term
Marketable securities:
Amortized Cost	60.7
Gross Unrealized Gains	0.0
Gross Unrealized Losses
Fair Value	60.7
Corporate debt securities | Long-term
Marketable securities:
Amortized Cost	44.7
Gross Unrealized Gains	0.0
Gross Unrealized Losses	(0.1)
Fair Value	44.6
Corporate debt securities | Level 1
Cash equivalents:
Fair Value	0.0
Corporate debt securities | Level 1 | Short-term
Marketable securities:
Fair Value	0.0
Corporate debt securities | Level 1 | Long-term
Marketable securities:
Fair Value	0.0
Corporate debt securities | Level 2
Cash equivalents:
Fair Value	17.6
Corporate debt securities | Level 2 | Short-term
Marketable securities:
Fair Value	60.7
Corporate debt securities | Level 2 | Long-term
Marketable securities:
Fair Value	44.6
Corporate debt securities | Level 3
Cash equivalents:
Fair Value	0.0
Corporate debt securities | Level 3 | Short-term
Marketable securities:
Fair Value	0.0
Corporate debt securities | Level 3 | Long-term
Marketable securities:
Fair Value	0.0
Certificates of deposit
Cash equivalents:
Amortized Cost	5.7
Fair Value	5.7
Certificates of deposit | Short-term
Marketable securities:
Amortized Cost	13.7
Gross Unrealized Gains	0.0
Gross Unrealized Losses	0.0
Fair Value	13.7
Certificates of deposit | Level 1
Cash equivalents:
Fair Value	0.0
Certificates of deposit | Level 1 | Short-term
Marketable securities:
Fair Value	0.0
Certificates of deposit | Level 2
Cash equivalents:
Fair Value	5.7
Certificates of deposit | Level 2 | Short-term
Marketable securities:
Fair Value	13.7
Certificates of deposit | Level 3
Cash equivalents:
Fair Value	0.0
Certificates of deposit | Level 3 | Short-term
Marketable securities:
Fair Value	0.0
Other
Cash equivalents:
Amortized Cost	4.0
Fair Value	4.0
Marketable securities:
Amortized Cost		4.0
Gross Unrealized Gains
Gross Unrealized Losses		0.0
Fair Value		4.0
Other | Short-term
Marketable securities:
Amortized Cost	4.2
Gross Unrealized Gains
Gross Unrealized Losses	0.0
Fair Value	4.2
Other | Long-term
Marketable securities:
Amortized Cost	0.8
Gross Unrealized Gains	0.0
Gross Unrealized Losses	0.0
Fair Value	0.8
Other | Level 1
Cash equivalents:
Fair Value	0.0
Marketable securities:
Fair Value
Other | Level 1 | Short-term
Marketable securities:
Fair Value
Other | Level 1 | Long-term
Marketable securities:
Fair Value	0.0
Other | Level 2
Cash equivalents:
Fair Value	4.0
Marketable securities:
Fair Value		4.0
Other | Level 2 | Short-term
Marketable securities:
Fair Value	4.2
Other | Level 2 | Long-term
Marketable securities:
Fair Value	0.8
Other | Level 3
Cash equivalents:
Fair Value	0.0
Marketable securities:
Fair Value		0.0
Other | Level 3 | Short-term
Marketable securities:
Fair Value	0.0
Other | Level 3 | Long-term
Marketable securities:
Fair Value	0.0
Asset backed securities | Short-term
Marketable securities:
Amortized Cost	26.3
Gross Unrealized Gains	0.0
Gross Unrealized Losses	0.0
Fair Value	26.3
Asset backed securities | Level 1 | Short-term
Marketable securities:
Fair Value	0.0
Asset backed securities | Level 2 | Short-term
Marketable securities:
Fair Value	26.3
Asset backed securities | Level 3 | Short-term
Marketable securities:
Fair Value	0.0
Municipal bonds | Short-term
Marketable securities:
Amortized Cost	11.1
Gross Unrealized Gains	0.0
Gross Unrealized Losses	0.0
Fair Value	11.1
Municipal bonds | Level 1 | Short-term
Marketable securities:
Fair Value	0.0
Municipal bonds | Level 2 | Short-term
Marketable securities:
Fair Value	11.1
Municipal bonds | Level 3 | Short-term
Marketable securities:
Fair Value	0.0
Common Stock | Short-term
Marketable securities:
Amortized Cost	0.0
Gross Unrealized Gains	4.3
Gross Unrealized Losses	0.0
Fair Value	4.3
Common Stock | Level 1 | Short-term
Marketable securities:
Fair Value	4.3
Common Stock | Level 2 | Short-term
Marketable securities:
Fair Value	0.0
Common Stock | Level 3 | Short-term
Marketable securities:
Fair Value	0.0
Mutual funds
Short-term trading securities
Amortized Cost	74.2	64.5
Gross Unrealized Gains	15.6	16.5
Gross Unrealized Losses	(0.3)	0.0
Fair Value	89.5	81.0
Mutual funds | Level 1
Short-term trading securities
Fair Value	89.5	81.0
Mutual funds | Level 2
Short-term trading securities
Fair Value	0.0	0.0
Mutual funds | Level 3
Short-term trading securities
Fair Value	$ 0.0	$ 0.0