Available-For-Sale And Held-To-Maturity Securities (Narrative) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2023 USD ($) Security	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Accrued interest receivable	$ 73,400		$ 65,700
Proceeds from sale of available-for-sale securities	10,000
Net realized gains (loss) resulting from sale of available-for-sale securities	7,600	$ 0
Financial instruments pledged as collateral	$ 769,400		796,200
Number of available for sale securities whose amortized costs exceeded their fair values | Security	282
Available-for-sale Securities, Continuous	$ 215,076
Available-for-sale Securities, Continuous Unrealized	206,680
Available-for-sale Securities, Continuous	$ 1,570,992
Percentage of available-for-sale portfolio	99.30%
Pledged [Member]
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Trading securities pledged	$ 1,300,000		1,300,000
Other Assets [Member]
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Accrued interest receivable	$ 90,400		$ 82,300