Derivatives and Hedging Activities - Notional Amounts and Estimated Fair Values of Derivatives (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Derivative [Line Items]
Derivative Asset, Notional Amount	$ 1,420.5	$ 2,144.7
Derivative Assets, Estimated Fair Value	44.9	37.4
Derivative Liability, Notional Amount	2,107.0	2,295.7
Net Liabilities in the Balance Sheet	133.8	127.3
Derivative Instruments and Hedges, Assets	194.7	193.3
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	5.3	6.7
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Assets, Estimated Fair Value	44.9	37.3
Net Liabilities in the Balance Sheet	133.8
Derivative Instruments and Hedges, Assets	850.0
Forward Contracts [Member]
Derivative [Line Items]
Derivative Assets, Estimated Fair Value		0.1
Net Liabilities in the Balance Sheet		0.1
Not Designated as Hedging Instrument | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	1,415.4	1,589.0
Derivative Assets, Estimated Fair Value	44.9	34.3
Derivative Liability, Notional Amount	1,415.4	1,589.0
Net Liabilities in the Balance Sheet	130.0	121.1
Not Designated as Hedging Instrument | Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	2.7	5.7
Derivative Assets, Estimated Fair Value	0.0	0.1
Not Designated as Hedging Instrument | Forward Contracts [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	2.4	0.0
Derivative Liability, Notional Amount	0.0	5.6
Net Liabilities in the Balance Sheet	0.0	0.1
Designated as Hedging Instrument | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	0.0	550.0
Derivative Assets, Estimated Fair Value	0.0	3.0
Derivative Liability, Notional Amount	300.0	300.0
Net Liabilities in the Balance Sheet	$ 2.8	$ 2.4