CONSOLIDATED STATEMENTS OF STOCKHOLDERS' (DEFICIT) EQUITY - USD ($) $ in Millions	Total	Cumulative effect, period of adoption, adjustment	Common stock and additional paid-in capital	Accumulated other comprehensive loss	Accumulated deficit	Accumulated deficit Cumulative effect, period of adoption, adjustment
Beginning Balance (in shares) at Jan. 31, 2018			218,300,000
Beginning Balance at Jan. 31, 2018	$ (256.0)	$ 177.5	$ 1,952.7	$ (123.8)	$ (2,084.9)	$ 177.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares issued under stock plans (in shares)			3,000,000.0
Common stock issued under stock plans	(52.5)		$ (52.5)
Stock-based compensation expense	249.5		249.5
Settlement of liability-classified restricted stock units	0.0
Pre-combination expense related to equity awards assumed	10.3		$ 10.3
Net income (loss)	(80.8)				(80.8)
Other comprehensive loss	(11.2)			(11.2)
Shares issued as consideration for business combination (in shares)			300,000
Shares issued as consideration for business combination	44.8		$ 44.8
Repurchase and retirement of common shares (in shares)			(2,200,000)
Repurchase and retirement of common stock	(292.5)		$ (133.3)		(159.2)
Ending Balance (in shares) at Jan. 31, 2019			219,400,000
Ending Balance at Jan. 31, 2019	(210.9)	$ (0.7)	$ 2,071.5	(135.0)	(2,147.4)	$ (0.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares issued under stock plans (in shares)			2,700,000
Common stock issued under stock plans	(18.6)		$ (18.6)
Stock-based compensation expense	332.7		332.7
Settlement of liability-classified restricted stock units	23.5		23.5
Pre-combination expense related to equity awards assumed	1.2		$ 1.2
Net income (loss)	214.5				214.5
Other comprehensive loss	(25.3)			(25.3)
Repurchase and retirement of common shares (in shares)			(2,700,000)
Repurchase and retirement of common stock	$ (455.5)		$ (93.3)		(362.2)
Ending Balance (in shares) at Jan. 31, 2020	219,400,000		219,400,000
Ending Balance at Jan. 31, 2020	$ (139.1)		$ 2,317.0	(160.3)	(2,295.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares issued under stock plans (in shares)			2,700,000
Common stock issued under stock plans	(41.2)		$ (41.2)
Stock-based compensation expense	385.6		385.6
Settlement of liability-classified restricted stock units	28.7		28.7
Pre-combination expense related to equity awards assumed	0.4		$ 0.4
Net income (loss)	1,208.2				1,208.2
Other comprehensive loss	34.4			34.4
Shares issued as consideration for business combination (in shares)			100,000
Shares issued as consideration for business combination	37.9		$ 37.9
Repurchase and retirement of common shares (in shares)			(2,600,000)
Repurchase and retirement of common stock	$ (549.4)		$ (149.5)		(399.9)
Ending Balance (in shares) at Jan. 31, 2021	219,600,000		219,600,000
Ending Balance at Jan. 31, 2021	$ 965.5		$ 2,578.9	$ (125.9)	$ (1,487.5)