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Securities - Amortized Cost and Fair Value of Securities (Details) - USD ($)
$ in Thousands
Sep. 30, 2024
Dec. 31, 2023
Securities available-for-sale [Abstract]    
Amortized Cost $ 5,560,376 $ 4,548,772
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax 26,339 26,982
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax 195,727 258,224
Fair Value 5,390,988 4,317,530
Available-for-sale, Amortized Cost [Abstract]    
Due in one year or less 5,075  
Due in one year to five years 227,176  
Due in five years to ten years 452,701  
Due after ten years 3,018,987  
Mortgage-backed securities 1,729,398  
Asset-backed securities 127,039  
Amortized Cost 5,560,376 4,548,772
Available-for-sale, Fair Value [Abstract]    
Due in one year or less 9,166  
Due in one year to five years 214,064  
Due in five years to ten years 425,872  
Due after ten years 2,958,917  
Mortgage-backed securities 1,654,357  
Asset-backed securities 128,612  
Fair Value 5,390,988 4,317,530
Securities held-to-maturity [Abstract]    
Amortized Cost 2,903,960 3,008,064
Gross Unrealized Gains 5,835 6,716
Gross Unrealized Losses 195,894 239,596
Fair Value 2,713,901 2,775,184
Allowance for credit losses - securities held-to-maturity 1,707 1,707
Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss 2,902,253 3,006,357
Held-to-maturity, Amortized Cost [Abstract]    
Due in one year or less 138,251  
Due in one year to five years 307,863  
Due in five years to ten years 80,695  
Due after ten years 1,830,161  
Mortgage-backed securities 370,433  
Asset-backed securities 176,557  
Amortized Cost 2,903,960 3,008,064
Held-to-maturity, Fair Value [Abstract]    
Due in one year or less 136,597  
Due in one year to five years 294,076  
Due in five years to ten years 75,397  
Due after ten years 1,692,721  
Mortgage-backed securities 345,291  
Asset-backed securities 169,819  
Fair Value 2,713,901 2,775,184
U.S. Treasury securities    
Securities available-for-sale [Abstract]    
Amortized Cost 1,456,514 907,990
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax 17 2
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax 24,974 14,580
Fair Value 1,431,557 893,412
Available-for-sale, Amortized Cost [Abstract]    
Amortized Cost 1,456,514 907,990
Available-for-sale, Fair Value [Abstract]    
Fair Value 1,431,557 893,412
Securities held-to-maturity [Abstract]    
Amortized Cost 69,974 90,309
Gross Unrealized Gains 0 0
Gross Unrealized Losses 1,348 3,840
Fair Value 68,626 86,469
Held-to-maturity, Amortized Cost [Abstract]    
Amortized Cost 69,974 90,309
Held-to-maturity, Fair Value [Abstract]    
Fair Value 68,626 86,469
U.S. Government agency securities    
Securities available-for-sale [Abstract]    
Amortized Cost 238,930 284,607
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax 5 0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax 18,132 21,877
Fair Value 220,803 262,730
Available-for-sale, Amortized Cost [Abstract]    
Amortized Cost 238,930 284,607
Available-for-sale, Fair Value [Abstract]    
Fair Value 220,803 262,730
Securities held-to-maturity [Abstract]    
Amortized Cost 340,158 364,769
Gross Unrealized Gains 0 0
Gross Unrealized Losses 10,979 19,187
Fair Value 329,179 345,582
Held-to-maturity, Amortized Cost [Abstract]    
Amortized Cost 340,158 364,769
Held-to-maturity, Fair Value [Abstract]    
Fair Value 329,179 345,582
Mortgage-backed securities    
Securities available-for-sale [Abstract]    
Amortized Cost 1,729,398 1,071,963
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax 10,878 444
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax 85,919 125,017
Fair Value 1,654,357 947,390
Available-for-sale, Amortized Cost [Abstract]    
Amortized Cost 1,729,398 1,071,963
Available-for-sale, Fair Value [Abstract]    
Fair Value 1,654,357 947,390
Securities held-to-maturity [Abstract]    
Amortized Cost 370,433 382,100
Gross Unrealized Gains 767 637
Gross Unrealized Losses 25,909 34,900
Fair Value 345,291 347,837
Held-to-maturity, Amortized Cost [Abstract]    
Amortized Cost 370,433 382,100
Held-to-maturity, Fair Value [Abstract]    
Fair Value 345,291 347,837
State and municipal securities    
Securities available-for-sale [Abstract]    
Amortized Cost 1,526,844 1,604,874
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax 11,819 26,129
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax 42,231 45,108
Fair Value 1,496,432 1,585,895
Available-for-sale, Amortized Cost [Abstract]    
Amortized Cost 1,526,844 1,604,874
Available-for-sale, Fair Value [Abstract]    
Fair Value 1,496,432 1,585,895
Securities held-to-maturity [Abstract]    
Amortized Cost 1,863,397 1,886,459
Gross Unrealized Gains 5,005 6,079
Gross Unrealized Losses 144,265 159,027
Fair Value 1,724,137 1,733,511
Held-to-maturity, Amortized Cost [Abstract]    
Amortized Cost 1,863,397 1,886,459
Held-to-maturity, Fair Value [Abstract]    
Fair Value 1,724,137 1,733,511
Asset-backed securities    
Securities available-for-sale [Abstract]    
Amortized Cost 127,039 201,577
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax 1,647 338
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax 74 10,280
Fair Value 128,612 191,635
Available-for-sale, Amortized Cost [Abstract]    
Amortized Cost 127,039 201,577
Available-for-sale, Fair Value [Abstract]    
Fair Value 128,612 191,635
Securities held-to-maturity [Abstract]    
Amortized Cost 176,557 198,418
Gross Unrealized Gains 63 0
Gross Unrealized Losses 6,801 14,228
Fair Value 169,819 184,190
Held-to-maturity, Amortized Cost [Abstract]    
Amortized Cost 176,557 198,418
Held-to-maturity, Fair Value [Abstract]    
Fair Value 169,819 184,190
Corporate notes and other    
Securities available-for-sale [Abstract]    
Amortized Cost 481,651 477,761
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax 1,973 69
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax 24,397 41,362
Fair Value 459,227 436,468
Available-for-sale, Amortized Cost [Abstract]    
Amortized Cost 481,651 477,761
Available-for-sale, Fair Value [Abstract]    
Fair Value 459,227 436,468
Securities held-to-maturity [Abstract]    
Amortized Cost 83,441 86,009
Gross Unrealized Gains 0 0
Gross Unrealized Losses 6,592 8,414
Fair Value 76,849 77,595
Held-to-maturity, Amortized Cost [Abstract]    
Amortized Cost 83,441 86,009
Held-to-maturity, Fair Value [Abstract]    
Fair Value $ 76,849 $ 77,595