Investments (Amortized Cost And Estimated Fair Value Of Debt Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Securities Available-for-Sale, Amortized Cost
Securities Available-for-Sale, Due in one year or less, Cost	$ 3,238
Securities Available-for-Sale, Due after one year through five years, Cost	18,566
Securities Available-for-Sale, Due after five years through ten years, Cost	156,128
Securities Available-for-Sale, Due after ten years, Cost	571,761
Securities Available-for-Sale, Cost, Total	749,693
Securities Available-for-Sale, Estimated Fair Value
Securities Available-for-Sale, Due in one year or less, Estimated Fair Value	3,241
Securities Available-for-Sale, Due after one year through five years, Estimated Fair Value	18,776
Securities Available-for-Sale, Due after five years through ten years, Estimated Fair Value	156,585
Securities Available-for-Sale, Due after ten years, Estimated Fair Value	571,268
Securities Available-for-Sale, Estimated Fair Value, Total	749,870
Securities Held-to-Maturity, Amortized Cost
Securities Held-to-Maturity, Due in one year or less, Cost	0
Securities Held-to-Maturity, Due after one year through five years, Cost	0
Securities Held-to-Maturity, Due after five years through ten years, Cost	4,929
Securities Held-to-Maturity, Due after ten years, Cost	50,397
Securities Held-to-Maturity, Amortized Cost	55,326	$ 60,827
Securities Held-to-Maturity, Estimated Fair Value
Securities Held-to-Maturity, Due in one year or less, Estimated Fair Value	0
Securities Held-to-Maturity, Due after one year through five years, Estimated Fair Value	0
Securities Held-to-Maturity, Due after five years through ten years, Estimated Fair Value	5,230
Securities Held-to-Maturity, Due after ten years, Estimated Fair Value	50,855
Securities Held-to-Maturity, Estimated Fair Value	$ 56,085	$ 60,706