Investment Securities (Amortization Cost And Estimated Fair Value Of Investment Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Schedule Of Amortized Cost And Estimated Fair Values [Line Items]
Available-for-Sale Securities, Amortized Cost	$ 678,400	$ 687,631
Available-for-Sale Securities, Gross Unrealized Gains	17,531	13,620
Available-for-Sale Securities, Gross Unrealized Losses	(16,468)	(3,707)
Available-for-Sale Securities, Fair value	679,463	697,544
Corporate Bonds [Member]
Schedule Of Amortized Cost And Estimated Fair Values [Line Items]
Available-for-Sale Securities, Amortized Cost	119,000	119,000
Available-for-Sale Securities, Gross Unrealized Losses	(16,318)	(3,170)
Available-for-Sale Securities, Fair value	102,682	115,830
State And Municipals [Member]
Schedule Of Amortized Cost And Estimated Fair Values [Line Items]
Available-for-Sale Securities, Amortized Cost	365,652	372,113
Available-for-Sale Securities, Gross Unrealized Gains	10,318	10,269
Available-for-Sale Securities, Gross Unrealized Losses	(127)	(239)
Available-for-Sale Securities, Fair value	375,843	382,143
Pass-Through Mortgage Securities [Member]
Schedule Of Amortized Cost And Estimated Fair Values [Line Items]
Available-for-Sale Securities, Amortized Cost	56,555	60,307
Available-for-Sale Securities, Gross Unrealized Gains	2,088	1,104
Available-for-Sale Securities, Gross Unrealized Losses		(39)
Available-for-Sale Securities, Fair value	58,643	61,372
Collateralized Mortgage Obligations [Member]
Schedule Of Amortized Cost And Estimated Fair Values [Line Items]
Available-for-Sale Securities, Amortized Cost	137,193	136,211
Available-for-Sale Securities, Gross Unrealized Gains	5,125	2,247
Available-for-Sale Securities, Gross Unrealized Losses	(23)	(259)
Available-for-Sale Securities, Fair value	$ 142,295	$ 138,199