Investment Securities (Amortized Cost And Fair Value Of Investment Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Available-for-sale, Amortized cost [Abstract]
Due before one year	$ 4,583
Due after one year through five years	114,902
Due after five years through ten years	222,239
Due after ten years	954,253
Total	1,295,977
Available-for-sale, Fair value [Abstract]
Due before one year	4,608
Due after one year through five years	121,416
Due after five years through ten years	231,130
Due after ten years	967,293
Fair value	1,324,447	$ 1,320,692
Held-to-maturity, Amortized cost [Abstract]
Due before one year
Due after one year through five years
Due after five years through ten years
Due after ten years
Held-to-maturity Securities, Total		84,387
Held-to-maturity, Fair value [Abstract]
Due before one year
Due after one year through five years
Due after five years through ten years
Due after ten years
Fair value		$ 83,002