Investment Securities (Narrative) (Details) $ in Millions	6 Months Ended
Jun. 30, 2025 USD ($) rental security	Dec. 31, 2024 USD ($)
Debt Securities, Available-for-sale [Line Items]
Number of positions \| security	393
Number of securities which impairment considered insignificant \| security	101
Available-for-sale securities, gross unrealized loss, considered insignificant \| $	$ 0.8
Securities in unrealized loss position \| $	330.0	$ 405.6
Accumulated gross unrealized gain (loss) \| $	75.6
Available-for-sale Securities
Debt Securities, Available-for-sale [Line Items]
Interest receivable \| $	31.0	36.0
Securities pledged as collateral \| $	$ 8,100.0	$ 7,900.0
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Number of positions	6
U.S. Government agency and sponsored enterprise residential MBS
Debt Securities, Available-for-sale [Line Items]
Number of positions	67
U.S. Government agency and sponsored enterprise commercial MBS
Debt Securities, Available-for-sale [Line Items]
Number of positions	20
SBA securities
Debt Securities, Available-for-sale [Line Items]
Number of positions	17
Private label residential MBS and CMOs
Debt Securities, Available-for-sale [Line Items]
Number of positions	115
Percentage of weighted average collateral loss	2.50%
Percentage of weighted average credit support	18.30%
Percentage of securities rated AAA	94.00%
Percentage of securities rated AA	4.00%
Percentage of securities rated A	1.00%
Number of Securities Not Rated	1
Private label commercial MBS
Debt Securities, Available-for-sale [Line Items]
Number of positions	40
Percentage of weighted average collateral loss	7.10%
Percentage of weighted average credit support	47.00%
Percentage of securities rated AAA	83.00%
Percentage of securities rated AA	15.00%
Percentage of securities rated A	2.00%
Single family real estate-backed securities
Debt Securities, Available-for-sale [Line Items]
Number of positions	7
Percentage of weighted average collateral loss	6.90%
Percentage of weighted average credit support	61.20%
Percentage of securities rated AAA	60.00%
Percentage of securities rated AA	40.00%
Collateralized loan obligations
Debt Securities, Available-for-sale [Line Items]
Number of positions	10
Percentage of weighted average collateral loss	14.20%
Percentage of weighted average credit support	41.40%
Percentage of securities rated AAA	85.00%
Percentage of securities rated AA	15.00%
Non-mortgage asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Number of positions	5
Percentage of weighted average collateral loss	3.70%
Percentage of weighted average credit support	31.60%
Percentage of securities rated AAA	26.00%
Percentage of securities rated AA	74.00%
State and municipal obligations
Debt Securities, Available-for-sale [Line Items]
Number of positions	5
Percentage of securities rated AA	100.00%

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Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

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