Corporate Investments and Funds Held For Clients (Corporate Investments And Funds Held For Clients) (Details) - USD ($) $ in Millions	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Money market securities, cash and other cash equivalents - amortized cost	$ 1,828.4	$ 1,436.3	$ 1,634.2
Amortized Cost	31,570.9	30,113.0
Gross Unrealized  Gains	34.8	9.7
Gross Unrealized Losses	(1,943.2)	(1,731.1)
Fair market value	29,662.5	28,391.6
Total corporate investments and funds held for clients - amortized cost	49,611.5	52,896.0
Total corporate investments and funds held for clients - gross unrealized gains	34.8	9.7
Total corporate investments and funds held for clients - gross unrealized losses	(1,943.2)	(1,731.1)
Total corporate investments and funds held for clients - fair market value	47,703.1	51,174.6
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	15,937.5	16,183.1
Gross Unrealized  Gains	12.6	3.9
Gross Unrealized Losses	(1,185.1)	(1,083.0)
Fair market value	14,765.0	15,104.0
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	7,607.1	5,003.6
Gross Unrealized  Gains	13.1	2.2
Gross Unrealized Losses	(230.0)	(171.1)
Fair market value	7,390.2	4,834.7
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,352.5	1,995.7
Gross Unrealized  Gains	0.4	0.5
Gross Unrealized Losses	(63.9)	(58.8)
Fair market value	1,289.0	1,937.4
Canadian government obligations and Canadian government agency obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,001.3	2,022.9
Gross Unrealized  Gains	2.0	0.1
Gross Unrealized Losses	(120.0)	(123.5)
Fair market value	1,883.3	1,899.5
U.S. government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,679.4	1,728.2
Gross Unrealized  Gains	0.9	0.1
Gross Unrealized Losses	(164.5)	(138.2)
Fair market value	1,515.8	1,590.1
Canadian provincial bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	973.4	994.3
Gross Unrealized  Gains	1.6	0.4
Gross Unrealized Losses	(63.1)	(62.7)
Fair market value	911.9	932.0
Commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	715.1	858.7
Gross Unrealized  Gains	0.0	0.3
Gross Unrealized Losses	(42.1)	(29.9)
Fair market value	673.0	829.1
Other securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,304.6	1,326.5
Gross Unrealized  Gains	4.2	2.2
Gross Unrealized Losses	(74.5)	(63.9)
Fair market value	1,234.3	1,264.8
Corporate Investments
Debt Securities, Available-for-sale [Line Items]
Fair market value	26.3	169.1
Funds Held For Clients
Debt Securities, Available-for-sale [Line Items]
Fair market value	29,636.2	28,222.5
Money Market Funds
Debt Securities, Available-for-sale [Line Items]
Money market securities, cash and other cash equivalents - amortized cost	18,040.6	22,783.0
Money market securities and other cash equivalents - fair market value	$ 18,040.6	$ 22,783.0