Derivative Financial Instruments and Hedging Activities - Summary of Derivatives (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Derivative [Line Items]
Notional balance	$ 7,320.9		$ 5,034.0
Derivatives, at fair value - See Note 15	39.5		28.1
Derivative liability, notional amount	3,655.9		4,186.6
Derivative liability, fair value	(27.0)		(9.1)
Gains (losses) on derivatives	(7.4)	$ 8.6
Forward Sales Of Reverse Loans
Derivative [Line Items]
Derivative liability, notional amount	0.0		30.0
Derivative liability, fair value	0.0		(0.2)
Gains (losses) on derivatives	0.2	(0.6)
Forward loans IRLCs
Derivative [Line Items]
Notional balance	2,707.8		2,461.9
Derivatives, at fair value - See Note 15	4.2		16.5
Gains (losses) on derivatives	(12.3)	8.9
Reverse loans IRLCs
Derivative [Line Items]
Notional balance	14.2		18.6
Derivatives, at fair value - See Note 15	0.8		0.8
Gains (losses) on derivatives	0.0	1.0
TBA forward MBS trades
Derivative [Line Items]
Notional balance	3,801.9		1,913.5
Derivatives, at fair value - See Note 15	28.4		8.4
Derivative liability, notional amount	1,480.9		2,171.6
Derivative liability, fair value	(8.0)		(6.6)
Interest Rate Swap
Derivative [Line Items]
Notional balance	597.0		590.0
Derivatives, at fair value - See Note 15	5.9		1.9
Derivative liability, notional amount	2,175.0		1,935.0
Derivative liability, fair value	(18.9)		(1.8)
Interest Rate Swap Futures And TBA Forward MBS Trades
Derivative [Line Items]
Gains (losses) on derivatives	(28.1)	20.8
Forward LHFS Trades
Derivative [Line Items]
Gains (losses) on derivatives	0.0	(1.7)
Interest rate option contracts
Derivative [Line Items]
Notional balance	200.0		50.0
Derivatives, at fair value - See Note 15	0.2		0.5
Derivative liability, notional amount	0.0		50.0
Derivative liability, fair value	0.0		$ (0.5)
Future
Derivative [Line Items]
Gains (losses) on derivatives	2.4	0.0
TRA Trades And Interest Rate Futures
Derivative [Line Items]
Gains (losses) on derivatives	$ 30.4	$ (19.9)

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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