Investments (Amortized Cost And Estimated Fair Value Of Debt Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Securities Available-for-Sale, Amortized Cost
Securities Available-for-Sale, Due in one year or less, Cost	$ 4,613
Securities Available-for-Sale, Due after one year through five years, Cost	14,247
Securities Available-for-Sale, Due after five years through ten years, Cost	80,868
Securities Available-for-Sale, Due after ten years, Cost	400,253
Securities Available-for-Sale, Cost, Total	499,981
Securities Available-for-Sale, Estimated Fair Value
Securities Available-for-Sale, Due in one year or less, Estimated Fair Value	2,639
Securities Available-for-Sale, Due after one year through five years, Estimated Fair Value	14,423
Securities Available-for-Sale, Due after five years through ten years, Estimated Fair Value	79,803
Securities Available-for-Sale, Due after ten years, Estimated Fair Value	401,398
Securities Available-for-Sale, Estimated Fair Value, Total	498,263
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	0
Securities Held-to-Maturity, Due after ten years, Cost	69,798
Securities Held-to-Maturity, Amortized Cost	69,798	$ 75,169
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	0
Securities Held-to-Maturity, Due after ten years, Estimated Fair Value	71,207
Securities Held-to-Maturity, Estimated Fair Value	$ 71,207	$ 76,445