Investment Securities (Schedule Of Contractual Maturities Of Investment Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt and Equity Securities, FV-NI [Line Items]
Available-for-sale securities, due within one year, amortized cost	$ 141,688
Available-for-sale securities, after one year through five years, amortized cost	2,259,829
Available-for-sale securities, after five years through ten years, amortized cost	2,187,571
Available-for-sale securities, after ten years, amortized cost	4,583,038
Available-for-sale securities, amortized cost	9,172,126	$ 9,262,777
Available-for-sale securities, due within one year, fair value	139,856
Available-for-sale securities, after one year through five years, fair value	2,213,929
Available-for-sale securities, after five years through ten years, fair value	2,103,386
Available-for-sale securities, after ten years, fair value	4,159,374
Debt Securities, Available-for-sale	8,616,545	8,829,870
Held-to-maturity securities, due within one year, amortized cost	0
Held-to-maturity securities, after one year through five years, amortized cost	2
Held-to-maturity securities, after five years through ten years, amortized cost	3
Held-to-maturity securities, after ten years, amortized cost	2,242
Investment securities held to maturity	2,247	2,300
Held-to-maturity securities, due within one year, fair value	0
Held-to-maturity securities, after one year through five years, fair value	2
Held-to-maturity securities, after five years through ten years, fair value	64
Held-to-maturity securities, after ten years, fair value	2,873
Held-to-maturity securities, fair value	$ 2,939	$ 3,025