For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Mortgage Loans Mortgage Loans Held for Sale (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Sep. 30, 2024
Mortgage loans held for sale	$ 2,767.7		$ 2,767.7		$ 2,477.5
Mortgage loans held for sale, outstanding principal amount	2,860.0		2,860.0		2,490.0
Payments for Origination of Mortgage Loans Held-for-sale			17,080.0	$ 17,730.0
Proceeds from Sale of Mortgage Loans Held-for-sale			16,680.0	17,680.0
Gain (Loss) on Sales of Loans, Net	152.8	$ 162.6	$ 423.9	$ 444.0
Loans Sold to FNMA, FHLMC or securities backed by GNMA [Member] \| Customer Concentration Risk \| Mortgage Loans
Concentration Risk, Percentage			72.00%
Other Customer [Member] \| Customer Concentration Risk \| Mortgage Loans
Concentration Risk, Percentage			26.00%
Loan Origination Commitments [Member]
Derivative, Notional Amount	880.5		$ 880.5		637.9
Fair Value, Inputs, Level 3 [Member] \| Interest rate lock commitments [Member]
Derivative, Notional Amount	2,700.0		2,700.0		2,000.0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Loan Origination Commitments [Member]
Interest Rate Derivative Instruments Not Designated as Hedging Instruments at Fair Value, Net	$ (6.8)		$ (6.8)		$ 2.4