Short-term Financing (Details) - USD ($)		3 Months Ended
		Sep. 30, 2019		Sep. 30, 2018	Jun. 30, 2019
Short-term Debt [Line Items]
Short-term debt		$ 0
Commercial paper		3,536,700,000	[1]		$ 0
Obligations under reverse repurchase agreements	[2]	$ 428,600,000			$ 262,000,000.0
Maturities of short-term funding agreements		overnight to up to five business days
364-day credit agreement
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities		$ 3,800,000,000
Term of credit agreement		364 days
Expiration date of credit facilities		Jun. 30, 2020
Extension option term		1 year
Credit Facility Expiring In June Two Thousand Twenty Four [Member]
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities		$ 2,750,000,000
Term of credit agreement		5 years
Expiration date of credit facilities		Jun. 30, 2024
Line of credit facility potentially available increase in maximum borrowing capacity		$ 500,000,000
Credit Facility Expiring In June Two Thousand Twenty Three [Member]
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities		$ 3,750,000,000
Term of credit agreement		5 years
Expiration date of credit facilities		Jun. 30, 2023
Line of credit facility potentially available increase in maximum borrowing capacity		$ 500,000,000
Commercial paper program
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities		$ 10,300,000,000
Maturities of commercial paper range		overnight to up to 364 days
Short-term debt, average outstanding amount		$ 4,000,000,000.0		$ 3,700,000,000
Debt instrument, interest rate during period		2.30%		2.00%
Short Term Commercial Paper Program
Short-term Debt [Line Items]
Commercial paper weighted average maturity		2 days		2 days
Reverse repurchase agreements
Short-term Debt [Line Items]
Short-term debt, average outstanding amount		$ 426,600,000		$ 495,100,000
Debt instrument, interest rate during period		2.00%		1.70%

[1] (B) The Company reclassified $3,535.5 million of funds held for clients to short-term marketable securities as a result of proceeds from commercial paper borrowings as of September 30, 2019 which were utilized to pay our client obligations.

[2] (A) As of September 30, 2019, $428.0 million of long-term marketable securities and $0.6 million of cash and cash equivalents have been pledged as collateral under the Company's reverse repurchase agreements. As of June 30, 2019, $261.4 million of long-term marketable securities and $0.6 million of cash and cash equivalents have been pledged as collateral under the Company's reverse repurchase agreements. Refer to Note 9