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Investment Securities (Schedule Of Fair Value And Unrealized Losses Of Securities) (Details) - USD ($) $ in Thousands | Dec. 31, 2023 | Dec. 31, 2022
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Investment Holdings [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | $ 1,292,794 | $ 1,486,583
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (12,009) | (143,817)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 2,809,244 | 1,660,143
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (476,099) | (398,532)
Debt Securities, Available-for-sale, Unrealized Loss Position | 4,102,038 | 3,146,726
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | (488,108) | (542,349)
U.S. Treasury and agencies |  |
Investment Holdings [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 99,898 | 734,473
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (1,074) | (71,967)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 822,245 | 201,701
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (77,800) | (27,391)
Debt Securities, Available-for-sale, Unrealized Loss Position | 922,143 | 936,174
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | (78,874) | (99,358)
Obligations of states and political subdivisions |  |
Investment Holdings [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 103,256 | 160,078
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (580) | (10,037)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 169,231 | 60,381
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (21,030) | (18,004)
Debt Securities, Available-for-sale, Unrealized Loss Position | 272,487 | 220,459
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | (21,610) | (28,041)
Mortgage-backed securities and collateralized mortgage obligations |  |
Investment Holdings [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 1,089,640 | 592,032
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (10,355) | (61,813)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 1,817,768 | 1,398,061
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (377,269) | (353,137)
Debt Securities, Available-for-sale, Unrealized Loss Position | 2,907,408 | 1,990,093
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | $ (387,624) | $ (414,950)

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