Derivatives and Hedging Activities - Notional Amounts and Estimated Fair Values of Derivatives (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Derivative [Line Items]
Derivative Asset, Notional Amount	$ 1,201.0	$ 1,420.5
Derivative Assets, Estimated Fair Value	26.6	44.9
Derivative Liability, Notional Amount	1,269.5	2,107.0
Net Liabilities in the Balance Sheet	77.3	133.8
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Assets, Estimated Fair Value	26.6	44.9
Net Liabilities in the Balance Sheet	77.3
Not Designated as Hedging Instrument | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	1,199.0	1,415.4
Derivative Assets, Estimated Fair Value	26.6	44.9
Derivative Liability, Notional Amount	1,204.9	1,415.4
Net Liabilities in the Balance Sheet	77.3	130.0
Not Designated as Hedging Instrument | Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	1.0	2.7
Derivative Assets, Estimated Fair Value	0.0	0.0
Not Designated as Hedging Instrument | Forward Contracts [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	1.0	2.4
Designated as Hedging Instrument | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	0.0	300.0
Net Liabilities in the Balance Sheet	$ 0.0	$ 2.8