Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions		Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]
Beginning balance, Shares at May. 31, 2020			358.8
Beginning balance at May. 31, 2020		$ 2,781.4	$ 3.6	$ 1,289.9	$ 1,431.4	$ 56.5
Net income		834.5			834.5
Unrealized losses on securities, net of tax benefit		(12.7)				(12.7)
Reclassification adjustment for realized gains on securities, net of tax expense	[1]	(0.8)				(0.8)
Cash dividends declared		(670.5)			(670.5)
Repurchases of common shares, Shares	[2]		(0.9)
Repurchases of common shares	[2]	(76.0)		(1.7)	(74.3)
Stock-based compensation costs		38.1		38.1
Foreign currency translation adjustment		14.2				14.2
Activity related to equity-based plans, Shares			2.4
Activity related to equity-based plans		68.2		90.0	(21.8)
Ending balance, Shares at Feb. 28, 2021			360.3
Ending balance at Feb. 28, 2021		2,976.4	$ 3.6	1,416.3	1,499.3	57.2
Beginning balance, Shares at Nov. 30, 2020			360.6
Beginning balance at Nov. 30, 2020		2,889.7	$ 3.6	1,394.1	1,418.9	73.1
Net income		350.5			350.5
Unrealized losses on securities, net of tax benefit		(20.0)				(20.0)
Reclassification adjustment for realized gains on securities, net of tax expense	[1]	(0.3)				(0.3)
Cash dividends declared		(223.8)			(223.8)
Repurchases of common shares, Shares	[2]		(0.5)
Repurchases of common shares	[2]	(47.2)		(1.0)	(46.2)
Stock-based compensation costs		12.6		12.6
Foreign currency translation adjustment		4.4				4.4
Activity related to equity-based plans, Shares			0.2
Activity related to equity-based plans		10.5		10.6	(0.1)
Ending balance, Shares at Feb. 28, 2021			360.3
Ending balance at Feb. 28, 2021		$ 2,976.4	$ 3.6	1,416.3	1,499.3	57.2
Beginning balance, Shares at May. 31, 2021		359.8	359.8
Beginning balance at May. 31, 2021		$ 2,948.0	$ 3.6	1,446.7	1,445.9	51.8
Net income		1,096.4			1,096.4
Unrealized losses on securities, net of tax benefit		(83.0)				(83.0)
Reclassification adjustment for realized gains on securities, net of tax expense	[3]	(0.1)				(0.1)
Cash dividends declared		(714.9)			(714.9)
Stock-based compensation costs		39.2		39.2
Foreign currency translation adjustment		(15.7)				(15.7)
Activity related to equity-based plans, Shares			1.2
Activity related to equity-based plans		$ 16.1	$ 0.0	45.0	(28.9)
Ending balance, Shares at Feb. 28, 2022		361.0	361.0
Ending balance at Feb. 28, 2022		$ 3,286.0	$ 3.6	1,530.9	1,798.5	(47.0)
Beginning balance, Shares at Nov. 30, 2021			360.8
Beginning balance at Nov. 30, 2021		3,119.8	$ 3.6	1,505.5	1,606.9	3.8
Net income		430.7			430.7
Unrealized losses on securities, net of tax benefit		(50.3)				(50.3)
Cash dividends declared		(238.5)			(238.5)
Stock-based compensation costs		12.8		12.8
Foreign currency translation adjustment		(0.5)				(0.5)
Activity related to equity-based plans, Shares			0.2
Activity related to equity-based plans		$ 12.0	$ 0.0	12.6	(0.6)
Ending balance, Shares at Feb. 28, 2022		361.0	361.0
Ending balance at Feb. 28, 2022		$ 3,286.0	$ 3.6	$ 1,530.9	$ 1,798.5	$ (47.0)

[1] Reclassification adjustments out of accumulated other comprehensive income for realized gains, net of tax, on the sale of AFS securities are reflected in interest on funds held for clients and other expense, net on the Consolidated Statements of Income and Comprehensive Income.

[2] The Company maintains two programs to repurchase up to $400.0 million of its common stock under each program, with authorization expiring on May 31, 2022 and January 31, 2024, respectively. The purpose of these programs is to manage common stock dilution. All shares of common stock repurchased were retired.

[3] Reclassification adjustments out of accumulated other comprehensive income for realized gains, net of tax, on the sale of available-for-sale (“AFS”) securities are reflected in interest on funds held for clients and other expense, net on the Consolidated Statements of Income and Comprehensive Income.