Investments (Amortized Cost And Estimated Fair Value Of Debt Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Investments [Abstract]
Securities Available-for-Sale, Due in one year or less, Cost	$ 1,610
Securities Available-for-Sale, Due after one year through five years, Cost	16,578
Securities Available-for-Sale, Due after five years through ten years, Cost	213,829
Securities Available-for-Sale, Due after ten years, Cost	559,859
Securities Available-for-Sale, Cost, Total	791,876
Securities Available-for-Sale, Due in one year or less, Estimated Fair Value	1,620
Securities Available-for-Sale, Due after one year through five years, Estimated Fair Value	17,017
Securities Available-for-Sale, Due after five years through ten years, Estimated Fair Value	217,872
Securities Available-for-Sale, Due after ten years, Estimated Fair Value	571,356
Securities Available-for-Sale, Estimated Fair Value, Total	807,865
Securities Held-to-Maturity, Due within One Year, Cost	0
Securities Held-to-Maturity, Due after One Through Five Years, Cost	0
Securities Held-to-Maturity, Due after five years through ten years, Cost	4,937
Securities Held-to-Maturity, Due after ten years, Cost	44,099
Securities Held-to-Maturity, Cost, Total	49,036	$ 60,827
Securities Held-to-Maturity, Due within One Year, Fair Value	0
Securities Held-to-Maturity, Due after One Through Five Years, Fair Value	0
Securities Held-to-Maturity, Due after five years through ten years, Estimated Fair Value	5,241
Securities Held-to-Maturity, Due after ten years, Estimated Fair Value	45,357
Securities held-to-maturity, Estimated Fair Value	$ 50,598	$ 60,706