Corporate Investments and Funds Held For Clients (Available-For-Sale Securities That Have Been In An Unrealized Loss Position) (Details) - USD ($)	Mar. 31, 2020		Jun. 30, 2019
Debt Securities, Available-for-sale [Line Items]
Unrealized losses less than 12 months	$ (76,000,000.0)		$ (7,200,000)
Fair market value of securities in unrealized loss position less than 12 months	4,933,600,000		1,107,700,000
Unrealized losses greater than 12 months	(1,000,000.0)		(25,900,000)
Fair market value of securities in unrealized loss positions greater than 12 months	296,800,000		7,192,500,000
Total gross unrealized losses	(77,000,000.0)		(33,100,000)
Total fair market value	5,230,400,000		8,300,200,000
Fair market value	24,023,600,000	[1]	24,859,100,000	[2]
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Unrealized losses less than 12 months	(32,900,000)		(600,000)
Fair market value of securities in unrealized loss position less than 12 months	2,811,000,000.0		151,900,000
Unrealized losses greater than 12 months	(100,000)		(6,100,000)
Fair market value of securities in unrealized loss positions greater than 12 months	12,000,000.0		2,055,600,000
Total gross unrealized losses	(33,000,000.0)		(6,700,000)
Total fair market value	2,823,000,000.0		2,207,500,000
Fair market value	10,995,800,000		10,867,900,000
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Unrealized losses less than 12 months	(41,200,000)		(200,000)
Fair market value of securities in unrealized loss position less than 12 months	1,954,600,000		171,900,000
Unrealized losses greater than 12 months	(900,000)		(5,200,000)
Fair market value of securities in unrealized loss positions greater than 12 months	281,600,000		2,083,500,000
Total gross unrealized losses	(42,100,000)		(5,400,000)
Total fair market value	2,236,200,000		2,255,400,000
Fair market value	4,042,000,000.0		4,690,700,000
U.S. government agency securities
Debt Securities, Available-for-sale [Line Items]
Unrealized losses less than 12 months	0		0
Fair market value of securities in unrealized loss position less than 12 months	2,500,000		1,800,000
Unrealized losses greater than 12 months	0		(8,000,000.0)
Fair market value of securities in unrealized loss positions greater than 12 months	0		1,159,400,000
Total gross unrealized losses	0		(8,000,000.0)
Total fair market value	2,500,000		1,161,200,000
Fair market value	3,715,300,000		2,948,800,000
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Unrealized losses less than 12 months	0		0
Fair market value of securities in unrealized loss position less than 12 months	0		0
Unrealized losses greater than 12 months	0		(5,800,000)
Fair market value of securities in unrealized loss positions greater than 12 months	0		1,671,400,000
Total gross unrealized losses	0		(5,800,000)
Total fair market value	0		1,671,400,000
Fair market value	1,552,400,000		2,623,900,000
Canadian government obligations and Canadian government agency obligations
Debt Securities, Available-for-sale [Line Items]
Unrealized losses less than 12 months	(300,000)		(6,000,000.0)
Fair market value of securities in unrealized loss position less than 12 months	24,600,000		662,700,000
Unrealized losses greater than 12 months	0		0
Fair market value of securities in unrealized loss positions greater than 12 months	0		1,100,000
Total gross unrealized losses	(300,000)		(6,000,000.0)
Total fair market value	24,600,000		663,800,000
Fair market value	1,022,900,000		1,165,100,000
Canadian provincial bonds
Debt Securities, Available-for-sale [Line Items]
Unrealized losses less than 12 months	0		(300,000)
Fair market value of securities in unrealized loss position less than 12 months	7,700,000		81,500,000
Unrealized losses greater than 12 months	0		(200,000)
Fair market value of securities in unrealized loss positions greater than 12 months	0		50,100,000
Total gross unrealized losses	0		(500,000)
Total fair market value	7,700,000		131,600,000
Fair market value	755,800,000		814,200,000
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Unrealized losses less than 12 months	(500,000)		0
Fair market value of securities in unrealized loss position less than 12 months	44,100,000		1,500,000
Unrealized losses greater than 12 months	0		(100,000)
Fair market value of securities in unrealized loss positions greater than 12 months	0		23,300,000
Total gross unrealized losses	(500,000)		(100,000)
Total fair market value	44,100,000		24,800,000
Fair market value	597,900,000		612,400,000
Other securities
Debt Securities, Available-for-sale [Line Items]
Unrealized losses less than 12 months	(1,100,000)		(100,000)
Fair market value of securities in unrealized loss position less than 12 months	89,100,000		36,400,000
Unrealized losses greater than 12 months	0		(500,000)
Fair market value of securities in unrealized loss positions greater than 12 months	3,200,000		148,100,000
Total gross unrealized losses	(1,100,000)		(600,000)
Total fair market value	92,300,000		184,500,000
Fair market value	1,341,500,000		$ 1,136,100,000
Fair Value, Inputs, Level 1
Debt Securities, Available-for-sale [Line Items]
Fair market value	0
Fair Value, Inputs, Level 3
Debt Securities, Available-for-sale [Line Items]
Fair market value	$ 0

[1] Included within available-for-sale securities are corporate investments with fair values of $3.2 million and funds held for clients with fair values of $24,020.4 million. All available-for-sale securities were included in Level 2 of the fair value hierarchy.

[2] Included within available-for-sale securities are corporate investments with fair values of $271.9 million and funds held for clients with fair values of $24,587.2 million. All available-for-sale securities were included in Level 2 of the fair value hierarchy.