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INVESTMENT SECURITIES - Equity and other securities (Details) - USD ($) $ in Thousands | Sep. 30, 2023 | Dec. 31, 2022
--- | --- | ---
Equity and Other Securities |  |
Amortized Cost | $ 66,006 | $ 82,424
Gross Unrealized Gains | 819 | 918
Gross Unrealized Losses | 0 | 0
Equity and other securities | 66,825 | 83,342
Equity Securities, at Fair Value |  |
Amortized Cost | 251 | 251
Gross Unrealized Gains | 69 | 168
Gross Unrealized Losses | 0 | 0
Fair Value | 320 | 419
Held-to-Maturity Portfolio: |  |
Amortized Cost | 1,125,540 |
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | 134,880 | 44,900
Fair Value | 990,660 | 1,034,795
Federal Home Loan Bank Common Stock |  |
Equity and Other Securities |  |
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | 0 | 0
Equity and other securities | 26,524 | 47,497
Other Equity Securities, at Adjusted Cost |  |
Amortized Cost | 26,524 | 47,497
Federal Reserve Bank Common Stock |  |
Equity and Other Securities |  |
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | 0 | 0
Equity and other securities | 33,568 | 31,144
Other Equity Securities, at Adjusted Cost |  |
Amortized Cost | 33,568 | 31,144
Other Equity Securities |  |
Equity and Other Securities |  |
Gross Unrealized Gains | 750 | 750
Gross Unrealized Losses | 0 | 0
Equity and other securities | 6,413 | 4,282
Other Equity Securities, at Adjusted Cost |  |
Amortized Cost | 5,663 | 3,532
U.S. Treasury and agency securities |  |
Held-to-Maturity Portfolio: |  |
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | 134,091 | 44,900
Fair Value | $ 967,588 | $ 1,034,795

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