Investment Securities (Schedule Of Contractual Maturities Of Investment Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Investment Holdings [Line Items]
Available-for-sale securities, due within one year, amortized cost	$ 32,935
Available-for-sale securities, after one year through five years, amortized cost	381,941
Available-for-sale securities, after five years through ten years, amortized cost	879,699
Available-for-sale securities, after ten years, amortized cost	2,411,519
Available-for-sale securities, amortized cost	3,706,094	$ 3,864,355
Available-for-sale securities, due within one year, fair value	31,768
Available-for-sale securities, after one year through five years, fair value	355,163
Available-for-sale securities, after five years through ten years, fair value	769,002
Available-for-sale securities, after ten years, fair value	1,980,458
Debt Securities, Available-for-sale	3,136,391	3,870,435
Held-to-maturity securities, due within one year, amortized cost	0
Held-to-maturity securities, after one year through five years, amortized cost	4
Held-to-maturity securities, after five years through ten years, amortized cost	3
Held-to-maturity securities, after ten years, amortized cost	2,540
Investment securities held to maturity	2,547	2,744
Held-to-maturity securities, due within one year, fair value	0
Held-to-maturity securities, after one year through five years, fair value	4
Held-to-maturity securities, after five years through ten years, fair value	3
Held-to-maturity securities, after ten years, fair value	3,280
Held-to-maturity securities, fair value	$ 3,287	$ 3,514