CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Retained Earnings	Accumulated Other Comprehensive Loss	Common Stock	Additional Paid-In Capital	Non- Controlling Interests
Beginning balance at Jan. 31, 2018	$ 3,248.2	$ 2,114.2	$ (138.0)	$ 1.2	$ 1,256.0	$ 14.8
Beginning balance (shares) at Jan. 31, 2018				124.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of restricted stock units	16.8				16.8
Exercise of stock options and vesting of restricted stock units (shares)				0.4
Shares withheld related to net share settlement of share-based compensation	(6.8)				(6.8)
Shares withheld related to net share settlement of share-based compensation (shares)				(0.1)
Share-based compensation expense	19.8				19.8
Purchase and retirement of Common Stock	$ (306.3)	(285.9)			(20.4)
Purchase and retirement of Common Stock (shares)	(2.4)			(2.4)
Cash dividends on Common Stock	$ (129.7)	(129.7)
Accrued dividends on share-based awards	(0.7)	(0.9)			0.2
Other comprehensive earnings (loss), net of tax	(60.5)		(60.5)
Net earnings	287.0	287.0
Non-controlling interests	(0.2)					(0.2)
Ending balance at Jul. 31, 2018	$ 3,071.5	1,986.8	(196.7)	$ 1.2	1,265.6	14.6
Ending balance (shares) at Jul. 31, 2018	122.4			122.4
Beginning balance at Apr. 30, 2018	$ 3,268.6	2,159.0	(166.1)	$ 1.2	1,259.6	14.9
Beginning balance (shares) at Apr. 30, 2018				124.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of restricted stock units	12.3				12.3
Exercise of stock options and vesting of restricted stock units (shares)				0.2
Shares withheld related to net share settlement of share-based compensation	(0.3)				(0.3)
Share-based compensation expense	10.8				10.8
Purchase and retirement of Common Stock	$ (265.9)	(248.9)			(17.0)
Purchase and retirement of Common Stock (shares)	(2.0)			(2.0)
Cash dividends on Common Stock	$ (67.5)	(67.5)
Accrued dividends on share-based awards	(0.3)	(0.5)			0.2
Other comprehensive earnings (loss), net of tax	(30.6)		(30.6)
Net earnings	144.7	144.7
Non-controlling interests	(0.3)					(0.3)
Ending balance at Jul. 31, 2018	$ 3,071.5	1,986.8	(196.7)	$ 1.2	1,265.6	14.6
Ending balance (shares) at Jul. 31, 2018	122.4			122.4
Beginning balance at Jan. 31, 2019	$ 3,130.9	2,045.6	(204.8)	$ 1.2	1,275.4	13.5
Beginning balance (shares) at Jan. 31, 2019	121.5			121.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of restricted stock units	$ 2.6				2.6
Exercise of stock options and vesting of restricted stock units (shares)				0.3
Shares withheld related to net share settlement of share-based compensation	(9.1)				(9.1)
Shares withheld related to net share settlement of share-based compensation (shares)				(0.1)
Share-based compensation expense	15.2				15.2
Purchase and retirement of Common Stock	$ (85.4)	(77.6)			(7.8)
Purchase and retirement of Common Stock (shares)	(0.9)			(0.9)
Cash dividends on Common Stock	$ (137.0)	(137.0)
Accrued dividends on share-based awards	(0.7)	(0.9)			0.2
Other comprehensive earnings (loss), net of tax	(6.2)		(6.2)
Net earnings	261.5	261.5
Non-controlling interests	(0.5)					(0.5)
Ending balance at Jul. 31, 2019	$ 3,193.1	2,139.4	(237.0)	$ 1.2	1,276.5	13.0
Ending balance (shares) at Jul. 31, 2019	120.8			120.8
Beginning balance at Apr. 30, 2019	$ 3,172.0	2,128.3	(244.0)	$ 1.2	1,273.1	13.4
Beginning balance (shares) at Apr. 30, 2019				121.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of restricted stock units	0.6				0.6
Shares withheld related to net share settlement of share-based compensation	(1.0)				(1.0)
Share-based compensation expense	9.3				9.3
Purchase and retirement of Common Stock	$ (60.0)	(54.5)			(5.5)
Purchase and retirement of Common Stock (shares)	(0.6)			(0.6)
Cash dividends on Common Stock	$ (70.2)	(70.2)
Accrued dividends on share-based awards	(0.5)	(0.5)
Other comprehensive earnings (loss), net of tax	7.0		7.0
Net earnings	136.3	136.3
Non-controlling interests	(0.4)					(0.4)
Ending balance at Jul. 31, 2019	$ 3,193.1	$ 2,139.4	$ (237.0)	$ 1.2	$ 1,276.5	$ 13.0
Ending balance (shares) at Jul. 31, 2019	120.8			120.8