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Investment Securities (Securities With Unrealized Losses And Length Of Impairment Period) (Details) - USD ($) $ in Thousands | Mar. 31, 2026 | Dec. 31, 2025
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | $ 1,443,027 | $ 659,636
Unrealized Loss, Less than 12 months | 9,633 | 2,704
Fair Value, Greater than 12 months | 4,904,458 | 5,222,367
Unrealized Loss, Greater than 12 months | 701,810 | 689,390
Debt Securities, Available-for-sale, Unrealized Loss Position | 6,347,485 | 5,882,003
Unrealized Loss on AFS Debt Securities | 711,443 | 692,094
U.S. government and federal agency obligations |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 1,321,452 | 612,167
Unrealized Loss, Less than 12 months | 9,277 | 2,620
Fair Value, Greater than 12 months | 190,275 | 314,006
Unrealized Loss, Greater than 12 months | 7,123 | 8,244
Debt Securities, Available-for-sale, Unrealized Loss Position | 1,511,727 | 926,173
Unrealized Loss on AFS Debt Securities | 16,400 | 10,864
Government-sponsored enterprise obligations |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 0 | 0
Unrealized Loss, Less than 12 months | 0 | 0
Fair Value, Greater than 12 months | 43,985 | 44,712
Unrealized Loss, Greater than 12 months | 10,614 | 10,239
Debt Securities, Available-for-sale, Unrealized Loss Position | 43,985 | 44,712
Unrealized Loss on AFS Debt Securities | 10,614 | 10,239
State and municipal obligations [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 30,515 | 12,157
Unrealized Loss, Less than 12 months | 118 | 18
Fair Value, Greater than 12 months | 614,192 | 636,492
Unrealized Loss, Greater than 12 months | 50,935 | 50,323
Debt Securities, Available-for-sale, Unrealized Loss Position | 644,707 | 648,649
Unrealized Loss on AFS Debt Securities | 51,053 | 50,341
Agency mortgage-backed securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 3,670 | 2,437
Unrealized Loss, Less than 12 months | 47 | 30
Fair Value, Greater than 12 months | 3,047,265 | 3,148,627
Unrealized Loss, Greater than 12 months | 578,793 | 565,056
Debt Securities, Available-for-sale, Unrealized Loss Position | 3,050,935 | 3,151,064
Unrealized Loss on AFS Debt Securities | 578,840 | 565,086
Non-Agency Mortgage-Backed Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 0 | 0
Unrealized Loss, Less than 12 months | 0 | 0
Fair Value, Greater than 12 months | 401,037 | 421,508
Unrealized Loss, Greater than 12 months | 31,665 | 31,942
Debt Securities, Available-for-sale, Unrealized Loss Position | 401,037 | 421,508
Unrealized Loss on AFS Debt Securities | 31,665 | 31,942
Asset-backed securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 68,558 | 32,875
Unrealized Loss, Less than 12 months | 181 | 36
Fair Value, Greater than 12 months | 514,421 | 546,984
Unrealized Loss, Greater than 12 months | 16,102 | 16,925
Debt Securities, Available-for-sale, Unrealized Loss Position | 582,979 | 579,859
Unrealized Loss on AFS Debt Securities | 16,283 | 16,961
Total Mortgage And Asset-Backed Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 72,228 | 35,312
Unrealized Loss, Less than 12 months | 228 | 66
Fair Value, Greater than 12 months | 3,962,723 | 4,117,119
Unrealized Loss, Greater than 12 months | 626,560 | 613,923
Debt Securities, Available-for-sale, Unrealized Loss Position | 4,034,951 | 4,152,431
Unrealized Loss on AFS Debt Securities | 626,788 | 613,989
Debt Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 18,832 | 0
Unrealized Loss, Less than 12 months | 10 | 0
Fair Value, Greater than 12 months | 93,283 | 110,038
Unrealized Loss, Greater than 12 months | 6,578 | 6,661
Debt Securities, Available-for-sale, Unrealized Loss Position | 112,115 | 110,038
Unrealized Loss on AFS Debt Securities | $ 6,588 | $ 6,661

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