Short-term Financing - Commercial Paper Program and Reverse Repurchase Agreements (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2024	Dec. 31, 2023
Commercial paper program
Short-term Debt [Line Items]
Average outstanding balances (in billions)	$ 4,500.0	$ 3,900.0	$ 4,700.0	$ 4,000.0
Weighted average interest rates	4.80%	5.40%	5.10%	5.30%
Weighted average maturity (approximately in days)	2 days	2 days	2 days	2 days
Reverse repurchase agreements
Short-term Debt [Line Items]
Average outstanding balances (in billions)	$ 3,700.0	$ 2,400.0	$ 3,700.0	$ 1,900.0
Weighted average interest rates	4.80%	5.40%	5.00%	5.40%