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Investment Securities (Investments Gross Unrealized Losses And Fair Value) (Details) - USD ($) $ in Thousands | Jun. 30, 2018 | Dec. 31, 2017
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Investment [Line Items] |  |
Securities available for sale, Less than 12 months, Fair Value | $ 368,967 | $ 319,678
Securities available for sale, Less than 12 months, Unrealized Losses | 11,813 | 2,618
Securities available for sale, 12 months or longer, Fair Value | 109,610 | 115,552
Securities available for sale, 12 months or longer, Unrealized Losses | 4,713 | 2,548
Securities available for sale, Fair Value, Total | 478,577 | 435,230
Securities available for sale, Unrealized Losses, Total | 16,526 | 5,166
Securities held to maturity, Less than 12 months, Fair Value | 130,465 | 113,419
Securities held to maturity, Less than 12 months, Unrealized Losses | 3,078 | 1,339
Securities held to maturity, 12 months or longer, Fair Value | 158,405 | 159,211
Securities held to maturity, 12 months or longer, Unrealized Losses | 7,483 | 4,485
Securities held to maturity, Fair Value, Total | 288,870 | 272,630
Securities held to maturity, Unrealized Losses, Total | 10,561 | 5,824
Total Securities, Less than 12 months, Fair Value | 499,432 | 433,097
Total Securities, Less than 12 months, Unrealized Losses | 14,891 | 3,957
Total Securities, 12 months or longer, Fair Value | 268,015 | 274,763
Total Securities, 12 months or longer, Unrealized Losses | 12,196 | 7,033
Total Securities, Fair Value | 767,447 | 707,860
Total Securities, Unrealized Losses | 27,087 | 10,990
U.S. Government Agencies And Government Sponsored Enterprises [Member] |  |
Investment [Line Items] |  |
Securities available for sale, Less than 12 months, Fair Value | 123,345 | 95,046
Securities available for sale, Less than 12 months, Unrealized Losses | 3,328 | 571
Securities available for sale, 12 months or longer, Fair Value | 30,701 | 31,561
Securities available for sale, 12 months or longer, Unrealized Losses | 1,487 | 687
Securities available for sale, Fair Value, Total | 154,046 | 126,607
Securities available for sale, Unrealized Losses, Total | 4,815 | 1,258
State And Political Subdivisions [Member] |  |
Investment [Line Items] |  |
Securities held to maturity, Less than 12 months, Fair Value | 65,548 | 36,368
Securities held to maturity, Less than 12 months, Unrealized Losses | 883 | 295
Securities held to maturity, 12 months or longer, Fair Value | 15,698 | 14,492
Securities held to maturity, 12 months or longer, Unrealized Losses | 676 | 367
Securities held to maturity, Fair Value, Total | 81,246 | 50,860
Securities held to maturity, Unrealized Losses, Total | 1,559 | 662
Collateralized Mortgage Obligations [Member] | Federal National Mortgage Association [Member] |  |
Investment [Line Items] |  |
Securities available for sale, 12 months or longer, Fair Value | 77 | 119
Securities available for sale, 12 months or longer, Unrealized Losses |  | 1
Securities available for sale, Fair Value, Total | 77 | 119
Securities available for sale, Unrealized Losses, Total |  | 1
Securities held to maturity, Less than 12 months, Fair Value | 16,268 | 16,830
Securities held to maturity, Less than 12 months, Unrealized Losses | 500 | 202
Securities held to maturity, 12 months or longer, Fair Value | 49,672 | 57,645
Securities held to maturity, 12 months or longer, Unrealized Losses | 2,466 | 1,756
Securities held to maturity, Fair Value, Total | 65,940 | 74,475
Securities held to maturity, Unrealized Losses, Total | 2,966 | 1,958
Collateralized Mortgage Obligations [Member] | Federal Home Loan Mortgage Corporation [Member] |  |
Investment [Line Items] |  |
Securities available for sale, 12 months or longer, Fair Value | 7 | 8
Securities available for sale, Fair Value, Total | 7 | 8
Securities held to maturity, Less than 12 months, Fair Value | 20,606 | 23,727
Securities held to maturity, Less than 12 months, Unrealized Losses | 799 | 337
Securities held to maturity, 12 months or longer, Fair Value | 61,513 | 66,467
Securities held to maturity, 12 months or longer, Unrealized Losses | 2,906 | 1,828
Securities held to maturity, Fair Value, Total | 82,119 | 90,194
Securities held to maturity, Unrealized Losses, Total | 3,705 | 2,165
Collateralized Mortgage Obligations [Member] | Government National Mortgage Association [Member] |  |
Investment [Line Items] |  |
Securities held to maturity, Less than 12 months, Fair Value | 6,940 | 15,401
Securities held to maturity, Less than 12 months, Unrealized Losses | 282 | 340
Securities held to maturity, 12 months or longer, Fair Value | 12,361 | 5,635
Securities held to maturity, 12 months or longer, Unrealized Losses | 529 | 162
Securities held to maturity, Fair Value, Total | 19,301 | 21,036
Securities held to maturity, Unrealized Losses, Total | 811 | 502
Mortgage-Backed Securities [Member] |  |
Investment [Line Items] |  |
Securities available for sale, Less than 12 months, Fair Value | 245,622 | 224,632
Securities available for sale, Less than 12 months, Unrealized Losses | 8,485 | 2,047
Securities available for sale, 12 months or longer, Fair Value | 78,909 | 83,991
Securities available for sale, 12 months or longer, Unrealized Losses | 3,226 | 1,861
Securities available for sale, Fair Value, Total | 324,531 | 308,623
Securities available for sale, Unrealized Losses, Total | 11,711 | 3,908
Securities held to maturity, Less than 12 months, Fair Value | 64,917 | 77,051
Securities held to maturity, Less than 12 months, Unrealized Losses | 2,195 | 1,044
Securities held to maturity, 12 months or longer, Fair Value | 142,707 | 144,719
Securities held to maturity, 12 months or longer, Unrealized Losses | 6,807 | 4,118
Securities held to maturity, Fair Value, Total | 207,624 | 221,770
Securities held to maturity, Unrealized Losses, Total | 9,002 | 5,162
Mortgage-Backed Securities [Member] | Federal National Mortgage Association [Member] |  |
Investment [Line Items] |  |
Securities available for sale, Less than 12 months, Fair Value | 219,797 | 201,754
Securities available for sale, Less than 12 months, Unrealized Losses | 7,637 | 1,855
Securities available for sale, 12 months or longer, Fair Value | 63,598 | 67,383
Securities available for sale, 12 months or longer, Unrealized Losses | 2,317 | 1,365
Securities available for sale, Fair Value, Total | 283,395 | 269,137
Securities available for sale, Unrealized Losses, Total | 9,954 | 3,220
Securities held to maturity, Less than 12 months, Fair Value | 7,662 | 3,766
Securities held to maturity, Less than 12 months, Unrealized Losses | 202 | 29
Securities held to maturity, 12 months or longer, Fair Value | 2,572 | 2,694
Securities held to maturity, 12 months or longer, Unrealized Losses | 138 | 59
Securities held to maturity, Fair Value, Total | 10,234 | 6,460
Securities held to maturity, Unrealized Losses, Total | 340 | 88
Mortgage-Backed Securities [Member] | Federal Home Loan Mortgage Corporation [Member] |  |
Investment [Line Items] |  |
Securities available for sale, Less than 12 months, Fair Value | 21,415 | 20,446
Securities available for sale, Less than 12 months, Unrealized Losses | 751 | 192
Securities available for sale, 12 months or longer, Fair Value | 14,438 | 15,601
Securities available for sale, 12 months or longer, Unrealized Losses | 904 | 483
Securities available for sale, Fair Value, Total | 35,853 | 36,047
Securities available for sale, Unrealized Losses, Total | 1,655 | 675
Securities held to maturity, Less than 12 months, Fair Value | 1,474 |
Securities held to maturity, Less than 12 months, Unrealized Losses | 13 |
Securities held to maturity, 12 months or longer, Fair Value | 2,962 | 3,094
Securities held to maturity, 12 months or longer, Unrealized Losses | 213 | 119
Securities held to maturity, Fair Value, Total | 4,436 | 3,094
Securities held to maturity, Unrealized Losses, Total | 226 | 119
Mortgage-Backed Securities [Member] | Government National Mortgage Association [Member] |  |
Investment [Line Items] |  |
Securities available for sale, Less than 12 months, Fair Value | 4,410 | 2,432
Securities available for sale, Less than 12 months, Unrealized Losses | 97 |
Securities available for sale, 12 months or longer, Fair Value | 789 | 880
Securities available for sale, 12 months or longer, Unrealized Losses | 5 | 12
Securities available for sale, Fair Value, Total | 5,199 | 3,312
Securities available for sale, Unrealized Losses, Total | 102 | 12
Securities held to maturity, Less than 12 months, Fair Value | 11,967 | 17,327
Securities held to maturity, Less than 12 months, Unrealized Losses | 399 | 136
Securities held to maturity, 12 months or longer, Fair Value | 13,627 | 9,184
Securities held to maturity, 12 months or longer, Unrealized Losses | 555 | 194
Securities held to maturity, Fair Value, Total | 25,594 | 26,511
Securities held to maturity, Unrealized Losses, Total | $ 954 | $ 330

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