Short-term Financing - Commercial Paper Program and Reverse Repurchase Agreements (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Commercial paper program
Short-term Debt [Line Items]
Short-term debt, average outstanding amount	$ 1,800.0	$ 3,500.0	$ 2,100.0	$ 3,700.0
Debt instrument, interest rate during period	0.10%	1.70%	0.10%	2.00%
Commercial paper weighted average maturity	1 day	2 days	1 day	2 days
Reverse repurchase agreements
Short-term Debt [Line Items]
Short-term debt, average outstanding amount	$ 83.2	$ 335.9	$ 117.8	$ 381.2
Debt instrument, interest rate during period	0.30%	1.70%	0.30%	1.80%