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Investment Securities, AFS and HTM Securities Amortized Costs and Fair Values (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2024 | Dec. 31, 2023
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | $ 4,251,409 | $ 3,749,814
Debt Securities, Available-for-Sale, Unrealized Gain | 31,500 | 24,579
Debt Securities, Available-for-Sale, Unrealized Loss | (130,382) | (173,501)
Debt Securities, Available-for-Sale | 4,152,527 | 3,600,892
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 3,769,224 | 3,860,235
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain | 48,682 | 55,619
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss | (465,131) | (535,230)
Debt Securities, Held-to-Maturity, Fair Value | 3,352,775 | 3,380,624
US Treasury Securities |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 39,987 | 39,984
Debt Securities, Available-for-Sale, Unrealized Gain | 0 | 0
Debt Securities, Available-for-Sale, Unrealized Loss | (3,039) | (4,083)
Debt Securities, Available-for-Sale | 36,948 | 35,902
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 1,000 | 999
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain | 0 | 0
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss | (10) | (36)
Debt Securities, Held-to-Maturity, Fair Value | 990 | 963
US States and Political Subdivisions Debt Securities [Member] |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 82,845 | 94,008
Debt Securities, Available-for-Sale, Unrealized Gain | 11 | 23
Debt Securities, Available-for-Sale, Unrealized Loss | (1,766) | (2,214)
Debt Securities, Available-for-Sale | 81,089 | 91,817
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 1,664,740 | 1,682,473
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain | 4,596 | 5,638
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss | (128,987) | (134,053)
Debt Securities, Held-to-Maturity, Fair Value | 1,540,348 | 1,554,059
Mortgage-backed Securities, Issued by Private Enterprises [Member] |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 0 |
Debt Securities, Available-for-Sale | 0 |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 329,349 | 345,083
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain | 8,519 | 9,796
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss | (55,765) | (65,372)
Debt Securities, Held-to-Maturity, Fair Value | 282,103 | 289,507
Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member] |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 113,139 | 135,832
Debt Securities, Available-for-Sale, Unrealized Gain | 132 | 5
Debt Securities, Available-for-Sale, Unrealized Loss | (922) | (1,862)
Debt Securities, Available-for-Sale | 112,350 | 133,975
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 |
Debt Securities, Held-to-Maturity, Fair Value | 0 |
US Government-sponsored Enterprises Debt Securities [Member] |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 540 | 1,077
Debt Securities, Available-for-Sale, Unrealized Gain | 0 | 2
Debt Securities, Available-for-Sale, Unrealized Loss | (24) | (28)
Debt Securities, Available-for-Sale | 516 | 1,051
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 |
Debt Securities, Held-to-Maturity, Fair Value | 0 |
Other Debt securities |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 3,000 | 3,000
Debt Securities, Available-for-Sale, Unrealized Gain | 0 | 0
Debt Securities, Available-for-Sale, Unrealized Loss | (3) | (50)
Debt Securities, Available-for-Sale | 2,997 | 2,950
US Government Sponsored-Enterprise Insured Loans | Residential Mortgage-Backed Securities [Member] |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 1,201,968 | 1,274,052
Debt Securities, Available-for-Sale, Unrealized Gain | 990 | 294
Debt Securities, Available-for-Sale, Unrealized Loss | (117,544) | (153,552)
Debt Securities, Available-for-Sale | 1,085,414 | 1,120,794
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 900,743 | 941,973
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain | 24,025 | 27,007
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss | (145,885) | (164,587)
Debt Securities, Held-to-Maturity, Fair Value | 778,883 | 804,393
US Government Sponsored-Enterprise Insured Loans | Commercial Mortgage-Backed Securities [Member] |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 18,423 | 18,691
Debt Securities, Available-for-Sale, Unrealized Gain | 0 | 0
Debt Securities, Available-for-Sale, Unrealized Loss | (388) | (1,755)
Debt Securities, Available-for-Sale | 18,035 | 16,937
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 775,209 | 780,995
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain | 11,142 | 12,699
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss | (126,498) | (160,781)
Debt Securities, Held-to-Maturity, Fair Value | 659,852 | 632,914
Government National Mortgage Association (GNMA) [Member] | Residential Mortgage-Backed Securities [Member] |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 2,634,634 | 2,021,242
Debt Securities, Available-for-Sale, Unrealized Gain | 30,367 | 24,254
Debt Securities, Available-for-Sale, Unrealized Loss | (1,441) | (2,822)
Debt Securities, Available-for-Sale | 2,663,560 | 2,042,675
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 45,180 | 48,979
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain | 143 | 92
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss | (2,344) | (2,901)
Debt Securities, Held-to-Maturity, Fair Value | 42,979 | 46,170
Government National Mortgage Association (GNMA) [Member] | Commercial Mortgage-Backed Securities [Member] |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 156,873 | 161,928
Debt Securities, Available-for-Sale, Unrealized Gain | 0 | 0
Debt Securities, Available-for-Sale, Unrealized Loss | (5,256) | (7,135)
Debt Securities, Available-for-Sale | 151,617 | 154,793
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 53,005 | 59,733
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain | 258 | 386
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss | (5,643) | (7,500)
Debt Securities, Held-to-Maturity, Fair Value | $ 47,620 | $ 52,619

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