Investment Securities (Amortized Cost And Fair Value Of Investment Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Available-for-sale, Amortized cost [Abstract]
Due before one year	$ 6,853
Due after one year through five years	83,690
Due after five years through ten years	236,008
Due after ten years	985,076
Total	1,311,627
Available-for-sale, Fair value [Abstract]
Due before one year	6,856
Due after one year through five years	85,246
Due after five years through ten years	239,505
Due after ten years	989,085
Fair value	1,320,692	$ 1,236,324
Held-to-maturity, Amortized cost [Abstract]
Due after ten years	84,387
Held-to-maturity Securities, Total	84,387	84,432
Held-to-maturity, Fair value [Abstract]
Due after ten years	83,002
Fair value	$ 83,002	$ 83,391