Derivatives and Hedging Activities - Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Derivative [Line Items]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax	$ 0.3	$ (4.4)
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	1.6
Financial Instruments	0.0		$ 0.0
Derivative Asset, Notional Amount	1,399.9		1,420.5
Derivative Asset, Estimated Fair Value	35.3		44.9
Derivative Liability, Notional Amount	2,086.4		2,107.0
Derivative Liabilities, Estimated Fair Value	107.3		133.8
Collateral Pledged
Derivative [Line Items]
Derivative, Fair Value, Net	0.0
Financial Instruments	0.0
Not Designated as Hedging Instrument
Derivative [Line Items]
Amount of net fee income recognized in other noninterest income	0.0	0.0
Interest Rate Swap
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	850.0
Interest Rate Swap | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	0.0		0.0
Derivative Asset, Estimated Fair Value	0.0		0.0
Derivative Liability, Notional Amount	300.0		300.0
Derivative Liabilities, Estimated Fair Value	1.0		2.8
Interest Rate Swap | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Notional Amount	1,390.7		1,415.4
Derivative Asset, Estimated Fair Value	35.2		44.9
Derivative Liability, Notional Amount	1,390.7		1,415.4
Derivative Liabilities, Estimated Fair Value	105.7		130.0
Risk Participation Agreements | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Liability, Notional Amount	89.0		91.6
Derivative Liabilities, Estimated Fair Value	0.0		0.0
Forward Contracts | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Fair Value, Net	0.0		0.0
Derivative Asset, Notional Amount	0.0		2.4
Derivative Liability, Notional Amount	6.7		0.0
Derivative Liabilities, Estimated Fair Value	0.0		0.0
Interest Rate Lock Commitments | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Notional Amount	9.2		2.7
Derivative Asset, Estimated Fair Value	0.1		0.0
Interest Rate Collars
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	300.0
Interest Rate Collars | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	300.0		300.0
Derivative Liabilities, Estimated Fair Value	0.6		$ 1.0
Cash Flow Hedging [Member] | Interest Rate Swap | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax	$ (1.0)	$ 17.4