Available-for-Sale and Held-to-Maturity Securities (Narrative) (Details)	12 Months Ended
	Dec. 31, 2024 USD ($) Security	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Allowance for credit losses	$ 0
Proceeds from sale of available-for-sale securities	0	$ 2,400,000	$ 80,000,000
Net realized gains (loss) resulting from sale of available-for-sale securities		(7,600,000)	$ 100,000
Accrued interest receivable	92,600,000	94,000,000
Financial instruments pledged as collateral	$ 842,300,000	746,400,000
Number of available for sale securities whose amortized costs exceeded their fair values | Security	251
Available-for-sale Securities, Continuous	$ 170,647,000
Available-for-sale Securities, Continuous	1,457,227,000
Available-for-sale Securities, Continuous Unrealized	$ 168,781,000
Percentage of available-for-sale portfolio	92.00%
Pledged [Member]
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Trading securities pledged	$ 2,200,000,000	1,300,000,000
Other Assets [Member]
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Accrued interest receivable	$ 106,800,000	$ 95,700,000