Investments (Aggregate Carrying And Approximate Market Values Of Available-For-Sale Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale, amortized cost	$ 1,130,155	$ 794,117
Available-for-sale debt securities, accumulated gross unrealized gain, before tax	49,336	18,210
Available-for-sale debt securities, accumulated gross unrealized loss, before tax	702	2,221
Available-for-sale Securities	1,178,789	810,106
U.S. Government agencies
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale, amortized cost	0	500
Available-for-sale debt securities, accumulated gross unrealized gain, before tax	0	2
Available-for-sale debt securities, accumulated gross unrealized loss, before tax	0	0
Available-for-sale Securities	0	502
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale, amortized cost	266,483	112,393
Available-for-sale debt securities, accumulated gross unrealized gain, before tax	11,467	4,800
Available-for-sale debt securities, accumulated gross unrealized loss, before tax	139	6
Available-for-sale Securities	277,811	117,187
U.S. Government agencies
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale, amortized cost	815,682	631,637
Available-for-sale debt securities, accumulated gross unrealized gain, before tax	34,807	12,292
Available-for-sale debt securities, accumulated gross unrealized loss, before tax	105	1,825
Available-for-sale Securities	850,384	642,104
Private label
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale, amortized cost	9,976	10,896
Available-for-sale debt securities, accumulated gross unrealized gain, before tax	916	589
Available-for-sale debt securities, accumulated gross unrealized loss, before tax	0	0
Available-for-sale Securities	10,892	11,485
Trust preferred securities
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale, amortized cost	4,557	4,781
Available-for-sale debt securities, accumulated gross unrealized gain, before tax	0	27
Available-for-sale debt securities, accumulated gross unrealized loss, before tax	457	347
Available-for-sale Securities	4,100	4,461
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale, amortized cost	31,465	31,669
Available-for-sale debt securities, accumulated gross unrealized gain, before tax	2,146	500
Available-for-sale debt securities, accumulated gross unrealized loss, before tax	1	43
Available-for-sale Securities	33,610	32,126
Debt Securities
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale, amortized cost	1,128,163	791,876
Available-for-sale debt securities, accumulated gross unrealized gain, before tax	49,336	18,210
Available-for-sale debt securities, accumulated gross unrealized loss, before tax	702	2,221
Available-for-sale Securities	1,176,797	807,865
Certificates of Deposit
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale, amortized cost	1,992	2,241
Available-for-sale debt securities, accumulated gross unrealized gain, before tax	0	0
Available-for-sale debt securities, accumulated gross unrealized loss, before tax	0	0
Available-for-sale Securities	$ 1,992	$ 2,241