Available-For-Sale And Held-To-Maturity Securities (Narrative) (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) Security	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Proceeds from sale of available-for-sale securities	$ 80,000,000.0		$ 491,900,000
Net realized gains (loss) resulting from sale of available-for-sale securities	100,000	$ 0	$ 500,000
Accrued interest receivable	65,700,000	27,400,000
Transfers from held to maturity to available for sale securities reclassification fair value		312,900,000
Gain On Transfer Of securities		0
Financial instruments pledged as collateral	$ 796,200,000	639,600,000
Number of available for sale securities whose amortized costs exceeded their fair values | Security	278
Available-for-sale Securities, Continuous	$ 227,329,000
Available-for-sale Securities, Continuous	1,619,763,000
Available-for-sale Securities, Continuous Unrealized	$ 183,022,000
Percentage of available-for-sale portfolio	99.00%
Pledged [Member]
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Trading securities pledged	$ 1,300,000,000	1,200,000,000
Other Assets [Member]
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Accrued interest receivable	$ 82,300,000	$ 29,100,000