INVESTMENT SECURITIES - Schedule of Held To Maturity Credit Quality Indicator (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Past due held-to-maturity debt securities	$ 1,068,879	$ 1,111,629
FNMA MBS
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Past due held-to-maturity debt securities	881,844	909,498
FNMA MBS | A+ rated or higher
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Past due held-to-maturity debt securities	0	0
FNMA MBS | Not rated
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Past due held-to-maturity debt securities	881,844	909,498
State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Past due held-to-maturity debt securities	187,035	201,631
State and political subdivisions | A+ rated or higher
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Past due held-to-maturity debt securities	187,035	201,631
State and political subdivisions | Not rated
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Past due held-to-maturity debt securities	$ 0	0
Foreign bonds
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Past due held-to-maturity debt securities		500
Foreign bonds | A+ rated or higher
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Past due held-to-maturity debt securities		500
Foreign bonds | Not rated
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Past due held-to-maturity debt securities		$ 0