Investments (Aggregate Carrying And Approximate Market Values Of Available-For-Sale Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 781,848	$ 732,853
Gross Unrealized Gains	17,025	3,153
Gross Unrealized Losses	2,636	14,210
Estimated Fair Value	796,237	721,796
U.S Treasuries and U.S. Government Agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,778	5,713
Gross Unrealized Gains	25	20
Gross Unrealized Losses	0	0
Estimated Fair Value	1,803	5,733
Obligations Of States And Political Subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	115,311	128,089
Gross Unrealized Gains	4,045	1,033
Gross Unrealized Losses	30	1,052
Estimated Fair Value	119,326	128,070
U.S. Government Agencies Mortgage-backed Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	627,953	561,799
Gross Unrealized Gains	11,898	1,950
Gross Unrealized Losses	1,949	12,991
Estimated Fair Value	637,902	550,758
Private Label
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	11,515	11,948
Gross Unrealized Gains	554	95
Gross Unrealized Losses	0	0
Estimated Fair Value	12,069	12,043
Trust Preferred Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,778	4,774
Gross Unrealized Gains	33	25
Gross Unrealized Losses	657	0
Estimated Fair Value	4,154	4,799
Corporate Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	16,778	16,795
Gross Unrealized Gains	470	30
Gross Unrealized Losses	0	167
Estimated Fair Value	17,248	16,658
Debt Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	778,113	729,118
Gross Unrealized Gains	17,025	3,153
Gross Unrealized Losses	2,636	14,210
Estimated Fair Value	792,502	718,061
Certificates of Deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,735	3,735
Estimated Fair Value	$ 3,735	$ 3,735