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Loans and Allowance for Credit Losses - Loan Balances by Year of Origination and Internally Assigned Risk Rating (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2024 | Mar. 31, 2023 | Dec. 31, 2023
Total Loan Balance |  |  |
Current fiscal year | $ 135,359 |  | $ 1,117,436
Year two | 1,138,128 |  | 1,320,936
Year three | 1,309,559 |  | 1,094,225
Year four | 1,059,734 |  | 503,703
Year five | 485,560 |  | 645,502
More than five years | 2,210,198 |  | 1,650,211
Revolving | 1,287,473 |  | 1,292,135
Revolving-Term | 30,023 |  | 29,193
Total | 7,656,034 |  | 7,653,341
Year-to-date Gross Charge-offs |  |  |
Current fiscal year | 191 |  | 830
Year two | 9 |  | 214
Year three | 27 |  | 218
Year four | 575 |  | 25
Year five | 17 |  | 3,989
More than five years | 5,417 |  | 18,669
Revolving | 500 |  | 109
Revolving-Term | 203 |  | 584
Total | 6,939 | $ 4,459 | 24,638
Pass |  |  |
Total Loan Balance |  |  |
Current fiscal year | 135,359 |  | 1,117,247
Year two | 1,135,064 |  | 1,318,412
Year three | 1,306,243 |  | 1,060,514
Year four | 1,026,435 |  | 499,034
Year five | 480,960 |  | 595,848
More than five years | 2,000,409 |  | 1,473,853
Revolving | 1,244,443 |  | 1,253,528
Revolving-Term | 26,766 |  | 25,838
Total | 7,355,679 |  | 7,344,274
Special mention |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 189
Year two | 3,064 |  | 1,681
Year three | 2,432 |  | 16,493
Year four | 17,177 |  | 224
Year five | 222 |  | 24,920
More than five years | 108,753 |  | 87,973
Revolving | 15,529 |  | 4,163
Revolving-Term | 165 |  | 172
Total | 147,342 |  | 135,815
Substandard |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 843
Year three | 884 |  | 17,218
Year four | 16,122 |  | 4,445
Year five | 4,378 |  | 24,734
More than five years | 101,036 |  | 88,385
Revolving | 27,501 |  | 34,444
Revolving-Term | 3,092 |  | 3,183
Total | 153,013 |  | 173,252
Doubtful |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 0
Year four | 0 |  | 0
Year five | 0 |  | 0
More than five years | 0 |  | 0
Revolving | 0 |  | 0
Revolving-Term | 0 |  | 0
Total | 0 |  | 0
Commercial Loans | Commercial real estate |  |  |
Total Loan Balance |  |  |
Current fiscal year | 25,970 |  | 276,677
Year two | 281,115 |  | 324,469
Year three | 351,226 |  | 439,308
Year four | 464,794 |  | 240,256
Year five | 228,899 |  | 419,371
More than five years | 1,313,640 |  | 926,636
Revolving | 34,138 |  | 32,418
Revolving-Term | 0 |  | 0
Total | 2,699,782 |  | 2,659,135
Year-to-date Gross Charge-offs |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 0
Year four | 0 |  | 0
Year five | 0 |  | 0
More than five years | 5,205 |  | 1,706
Revolving | 0 |  | 0
Revolving-Term | 0 |  | 0
Total | 5,205 | 0 | 1,706
Commercial Loans | Commercial and industrial |  |  |
Total Loan Balance |  |  |
Current fiscal year | 13,824 |  | 171,861
Year two | 174,698 |  | 231,978
Year three | 227,563 |  | 210,636
Year four | 188,869 |  | 54,696
Year five | 52,253 |  | 52,858
More than five years | 228,371 |  | 193,905
Revolving | 524,939 |  | 520,249
Revolving-Term | 0 |  | 0
Total | 1,410,517 |  | 1,436,183
Year-to-date Gross Charge-offs |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 0
Year four | 537 |  | 0
Year five | 0 |  | 3,412
More than five years | 91 |  | 15,842
Revolving | 500 |  | 0
Revolving-Term | 0 |  | 0
Total | 1,128 | 3,412 | 19,254
Commercial Loans | Commercial construction |  |  |
Total Loan Balance |  |  |
Current fiscal year | 13,086 |  | 75,596
Year two | 90,954 |  | 154,456
Year three | 141,982 |  | 82,313
Year four | 65,353 |  | 14,845
Year five | 14,758 |  | 4,727
More than five years | 9,008 |  | 4,438
Revolving | 12,234 |  | 14,208
Revolving-Term | 0 |  | 0
Total | 347,375 |  | 350,583
Year-to-date Gross Charge-offs |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 0
Year four | 0 |  | 0
Year five | 0 |  | 451
More than five years | 0 |  | 0
Revolving | 0 |  | 0
Revolving-Term | 0 |  | 0
Total | 0 | 0 | 451
Commercial Loans | Business banking |  |  |
Total Loan Balance |  |  |
Current fiscal year | 32,910 |  | 270,129
Year two | 254,296 |  | 262,606
Year three | 241,359 |  | 207,611
Year four | 190,039 |  | 88,018
Year five | 85,071 |  | 99,574
More than five years | 407,132 |  | 334,766
Revolving | 95,068 |  | 96,754
Revolving-Term | 1,280 |  | 1,307
Total | 1,307,155 |  | 1,360,765
Year-to-date Gross Charge-offs |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 67
Year three | 0 |  | 43
Year four | 0 |  | 1
Year five | 0 |  | 88
More than five years | 98 |  | 1,073
Revolving | 0 |  | 34
Revolving-Term | 0 |  | 0
Total | 98 | 652 | 1,306
Commercial Loans | Pass | Commercial real estate |  |  |
Total Loan Balance |  |  |
Current fiscal year | 25,970 |  | 276,677
Year two | 281,115 |  | 323,463
Year three | 349,797 |  | 433,308
Year four | 458,810 |  | 237,901
Year five | 226,569 |  | 383,799
More than five years | 1,144,226 |  | 781,465
Revolving | 34,138 |  | 32,418
Revolving-Term | 0 |  | 0
Total | 2,520,625 |  | 2,469,031
Commercial Loans | Pass | Commercial and industrial |  |  |
Total Loan Balance |  |  |
Current fiscal year | 13,824 |  | 171,672
Year two | 173,323 |  | 231,114
Year three | 226,390 |  | 185,884
Year four | 165,616 |  | 53,101
Year five | 50,753 |  | 47,063
More than five years | 212,441 |  | 183,165
Revolving | 482,770 |  | 482,490
Revolving-Term | 0 |  | 0
Total | 1,325,117 |  | 1,354,489
Commercial Loans | Pass | Commercial construction |  |  |
Total Loan Balance |  |  |
Current fiscal year | 13,086 |  | 75,596
Year two | 90,954 |  | 154,456
Year three | 141,982 |  | 82,313
Year four | 65,353 |  | 14,845
Year five | 14,758 |  | 151
More than five years | 4,048 |  | 4,054
Revolving | 12,234 |  | 14,208
Revolving-Term | 0 |  | 0
Total | 342,415 |  | 345,623
Commercial Loans | Pass | Business banking |  |  |
Total Loan Balance |  |  |
Current fiscal year | 32,910 |  | 270,129
Year two | 252,607 |  | 262,535
Year three | 241,227 |  | 204,874
Year four | 186,203 |  | 87,346
Year five | 84,354 |  | 96,371
More than five years | 392,973 |  | 321,360
Revolving | 94,920 |  | 96,618
Revolving-Term | 508 |  | 523
Total | 1,285,702 |  | 1,339,756
Commercial Loans | Special mention | Commercial real estate |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 1,006
Year three | 1,429 |  | 6,000
Year four | 5,984 |  | 0
Year five | 0 |  | 24,887
More than five years | 95,502 |  | 75,428
Revolving | 0 |  | 0
Revolving-Term | 0 |  | 0
Total | 102,915 |  | 107,321
Commercial Loans | Special mention | Commercial and industrial |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 189
Year two | 1,375 |  | 620
Year three | 949 |  | 10,242
Year four | 9,849 |  | 0
Year five | 0 |  | 0
More than five years | 9,831 |  | 8,848
Revolving | 15,485 |  | 4,126
Revolving-Term | 0 |  | 0
Total | 37,489 |  | 24,025
Commercial Loans | Special mention | Commercial construction |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 0
Year four | 0 |  | 0
Year five | 0 |  | 0
More than five years | 0 |  | 0
Revolving | 0 |  | 0
Revolving-Term | 0 |  | 0
Total | 0 |  | 0
Commercial Loans | Special mention | Business banking |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 1,689 |  | 55
Year three | 54 |  | 251
Year four | 1,344 |  | 224
Year five | 222 |  | 33
More than five years | 3,311 |  | 3,508
Revolving | 44 |  | 37
Revolving-Term | 165 |  | 172
Total | 6,829 |  | 4,280
Commercial Loans | Substandard | Commercial real estate |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 0
Year four | 0 |  | 2,355
Year five | 2,330 |  | 10,685
More than five years | 73,912 |  | 69,743
Revolving | 0 |  | 0
Revolving-Term | 0 |  | 0
Total | 76,242 |  | 82,783
Commercial Loans | Substandard | Commercial and industrial |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 244
Year three | 224 |  | 14,510
Year four | 13,404 |  | 1,595
Year five | 1,500 |  | 5,795
More than five years | 6,099 |  | 1,892
Revolving | 26,684 |  | 33,633
Revolving-Term | 0 |  | 0
Total | 47,911 |  | 57,669
Commercial Loans | Substandard | Commercial construction |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 0
Year four | 0 |  | 0
Year five | 0 |  | 4,576
More than five years | 4,960 |  | 384
Revolving | 0 |  | 0
Revolving-Term | 0 |  | 0
Total | 4,960 |  | 4,960
Commercial Loans | Substandard | Business banking |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 16
Year three | 78 |  | 2,486
Year four | 2,492 |  | 448
Year five | 495 |  | 3,170
More than five years | 10,848 |  | 9,898
Revolving | 104 |  | 99
Revolving-Term | 607 |  | 612
Total | 14,624 |  | 16,729
Commercial Loans | Doubtful | Commercial real estate |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 0
Year four | 0 |  | 0
Year five | 0 |  | 0
More than five years | 0 |  | 0
Revolving | 0 |  | 0
Revolving-Term | 0 |  | 0
Total | 0 |  | 0
Commercial Loans | Doubtful | Commercial and industrial |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 0
Year four | 0 |  | 0
Year five | 0 |  | 0
More than five years | 0 |  | 0
Revolving | 0 |  | 0
Revolving-Term | 0 |  | 0
Total | 0 |  | 0
Commercial Loans | Doubtful | Commercial construction |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 0
Year four | 0 |  | 0
Year five | 0 |  | 0
More than five years | 0 |  | 0
Revolving | 0 |  | 0
Revolving-Term | 0 |  | 0
Total | 0 |  | 0
Commercial Loans | Doubtful | Business banking |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 0
Year four | 0 |  | 0
Year five | 0 |  | 0
More than five years | 0 |  | 0
Revolving | 0 |  | 0
Revolving-Term | 0 |  | 0
Total | 0 |  | 0
Consumer Loans | Consumer real estate |  |  |
Total Loan Balance |  |  |
Current fiscal year | 46,543 |  | 311,887
Year two | 327,577 |  | 335,462
Year three | 336,640 |  | 147,850
Year four | 145,121 |  | 102,041
Year five | 101,308 |  | 67,890
More than five years | 250,783 |  | 189,794
Revolving | 549,482 |  | 552,080
Revolving-Term | 25,519 |  | 24,774
Total | 1,782,973 |  | 1,731,778
Year-to-date Gross Charge-offs |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 1
Year three | 0 |  | 0
Year four | 0 |  | 5
Year five | 9 |  | 1
More than five years | 14 |  | 43
Revolving | 0 |  | 75
Revolving-Term | 116 |  | 296
Total | 139 | 77 | 421
Consumer Loans | Other consumer |  |  |
Total Loan Balance |  |  |
Current fiscal year | 3,026 |  | 11,286
Year two | 9,488 |  | 11,965
Year three | 10,789 |  | 6,507
Year four | 5,558 |  | 3,847
Year five | 3,271 |  | 1,082
More than five years | 1,264 |  | 672
Revolving | 71,612 |  | 76,426
Revolving-Term | 3,224 |  | 3,112
Total | 108,232 |  | 114,897
Year-to-date Gross Charge-offs |  |  |
Current fiscal year | 191 |  | 830
Year two | 9 |  | 146
Year three | 27 |  | 175
Year four | 38 |  | 19
Year five | 8 |  | 37
More than five years | 9 |  | 5
Revolving | 0 |  | 0
Revolving-Term | 87 |  | 288
Total | 369 | $ 318 | 1,500
Consumer Loans | Pass | Consumer real estate |  |  |
Total Loan Balance |  |  |
Current fiscal year | 46,543 |  | 311,887
Year two | 327,577 |  | 334,879
Year three | 336,058 |  | 147,652
Year four | 144,925 |  | 101,999
Year five | 101,267 |  | 67,402
More than five years | 245,620 |  | 183,283
Revolving | 548,769 |  | 551,368
Revolving-Term | 23,048 |  | 22,206
Total | 1,773,807 |  | 1,720,676
Consumer Loans | Pass | Other consumer |  |  |
Total Loan Balance |  |  |
Current fiscal year | 3,026 |  | 11,286
Year two | 9,488 |  | 11,965
Year three | 10,789 |  | 6,483
Year four | 5,528 |  | 3,842
Year five | 3,259 |  | 1,062
More than five years | 1,101 |  | 526
Revolving | 71,612 |  | 76,426
Revolving-Term | 3,210 |  | 3,109
Total | 108,013 |  | 114,699
Consumer Loans | Special mention | Consumer real estate |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 0
Year four | 0 |  | 0
Year five | 0 |  | 0
More than five years | 109 |  | 189
Revolving | 0 |  | 0
Revolving-Term | 0 |  | 0
Total | 109 |  | 189
Consumer Loans | Special mention | Other consumer |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 0
Year four | 0 |  | 0
Year five | 0 |  | 0
More than five years | 0 |  | 0
Revolving | 0 |  | 0
Revolving-Term | 0 |  | 0
Total | 0 |  | 0
Consumer Loans | Substandard | Consumer real estate |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 583
Year three | 582 |  | 198
Year four | 196 |  | 42
Year five | 41 |  | 488
More than five years | 5,054 |  | 6,322
Revolving | 713 |  | 712
Revolving-Term | 2,471 |  | 2,568
Total | 9,057 |  | 10,913
Consumer Loans | Substandard | Other consumer |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 24
Year four | 30 |  | 5
Year five | 12 |  | 20
More than five years | 163 |  | 146
Revolving | 0 |  | 0
Revolving-Term | 14 |  | 3
Total | 219 |  | 198
Consumer Loans | Doubtful | Consumer real estate |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 0
Year four | 0 |  | 0
Year five | 0 |  | 0
More than five years | 0 |  | 0
Revolving | 0 |  | 0
Revolving-Term | 0 |  | 0
Total | 0 |  | 0
Consumer Loans | Doubtful | Other consumer |  |  |
Total Loan Balance |  |  |
Current fiscal year | 0 |  | 0
Year two | 0 |  | 0
Year three | 0 |  | 0
Year four | 0 |  | 0
Year five | 0 |  | 0
More than five years | 0 |  | 0
Revolving | 0 |  | 0
Revolving-Term | 0 |  | 0
Total | $ 0 |  | $ 0

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