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Securities (Summary of Gross Unrealized Losses and Fair Value of the Investments with Unrealized Losses) (Details) - USD ($) $ in Thousands | Mar. 31, 2022 | Dec. 31, 2021
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Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | $ 4,159,679 | $ 3,195,732
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 286,863 | 43,236
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 516,421 | 383,754
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 50,604 | 14,645
Debt Securities, Available-for-sale, Unrealized Loss Position | 4,676,100 | 3,579,486
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | 337,467 | 57,881
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 2,667,464 | 2,292,062
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 181,337 | 30,777
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 214,390 | 176,946
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 23,900 | 7,315
Debt Securities, Available-for-sale, Unrealized Loss Position | 2,881,854 | 2,469,008
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | 205,237 | 38,092
Asset-backed Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 277,210 | 195,708
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 16,208 | 4,823
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 106,449 | 117,751
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 10,001 | 4,968
Debt Securities, Available-for-sale, Unrealized Loss Position | 383,659 | 313,459
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | 26,209 | 9,791
State and Municipal Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 657,101 | 237,354
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 57,012 | 3,862
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 77,447 | 40,343
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 8,788 | 1,076
Debt Securities, Available-for-sale, Unrealized Loss Position | 734,548 | 277,697
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | 65,800 | 4,938
U.S. Government and Government-Sponsored Enterprise Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 25,502 | 100,813
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 1,249 | 1,988
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 118,135 | 48,714
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 7,915 | 1,286
Debt Securities, Available-for-sale, Unrealized Loss Position | 143,637 | 149,527
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | 9,164 | 3,274
US Treasury Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 173,342 | 157,536
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 9,158 | 831
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | 0
Debt Securities, Available-for-sale, Unrealized Loss Position | 173,342 | 157,536
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | 9,158 | 831
Non-agency collateralized mortgage obligations [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 359,060 | 212,259
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 21,899 | 955
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | 0
Debt Securities, Available-for-sale, Unrealized Loss Position | 359,060 | 212,259
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | $ 21,899 | $ 955

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