Statements of Consolidated Earnings - USD ($) shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
REVENUES:
TOTAL REVENUES		$ 4,668.0	$ 4,391.0	$ 9,180.3	$ 8,606.6
Costs of revenues:
Operating expenses		2,213.3	2,134.5	4,370.9	4,209.0
Research and development		228.7	204.2	465.1	413.9
Depreciation and amortization		119.6	112.0	240.9	221.4
TOTAL COSTS OF REVENUES		2,561.6	2,450.7	5,076.9	4,844.3
Selling, general, and administrative expenses		922.5	855.7	1,802.8	1,656.1
Interest expense		104.9	57.0	196.5	108.1
TOTAL EXPENSES		3,589.0	3,363.4	7,076.2	6,608.5
Other (income)/expense, net		(64.8)	(30.5)	(132.5)	(70.0)
EARNINGS BEFORE INCOME TAXES		1,143.8	1,058.1	2,236.6	2,068.1
Provision for income taxes		265.4	245.0	498.8	475.9
NET EARNINGS		$ 878.4	$ 813.1	$ 1,737.8	$ 1,592.2
Earnings Per Share [Abstract]
BASIC EARNINGS PER SHARE (in USD per share)		$ 2.14	$ 1.96	$ 4.22	$ 3.84
DILUTED EARNINGS PER SHARE (in USD per share)		$ 2.13	$ 1.95	$ 4.20	$ 3.82
Basic weighted average shares outstanding (in shares)		411.1	414.3	411.4	414.4
Diluted weighted average shares outstanding (shares)		412.5	416.2	414.0	416.6
Revenues, other than interest on funds held for clients and PEO revenues
REVENUES:
TOTAL REVENUES		$ 2,898.6	$ 2,702.2	$ 5,741.4	$ 5,348.6
Interest on funds held for clients
REVENUES:
TOTAL REVENUES		225.3	187.2	427.1	328.3
PEO Revenues
REVENUES:
TOTAL REVENUES	[1]	$ 1,544.1	$ 1,501.6	$ 3,011.8	$ 2,929.7

[1] Professional Employer Organization (“PEO”) revenues are net of direct pass-through costs, primarily consisting of payroll wages and payroll taxes of $18,379.2 million and $17,852.4 million for the three months ended December 31, 2023 and 2022, respectively, and $34,373.8 million and $33,386.6 million for the six months ended December 31, 2023 and 2022, respectively.