INVESTMENT SECURITIES - Amortized Cost of Investment Securities Held to Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 2,184,497	$ 2,287,372
Aaa
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	185,143
Aa1
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	150,821
Aa2
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	178,461
Aa3
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	133,439
A1
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	131,314
A2
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	16,834
A3
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	3,467
Non-rated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,385,018
State and municipal
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,099,201	$ 1,117,552
State and municipal | Aaa
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	114,557
State and municipal | Aa1
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	150,821
State and municipal | Aa2
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	178,461
State and municipal | Aa3
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	133,439
State and municipal | A1
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	131,314
State and municipal | A2
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	16,834
State and municipal | A3
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	3,467
State and municipal | Non-rated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	370,308
Other
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,085,296
Other | Aaa
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	70,586
Other | Aa1
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Other | Aa2
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Other | Aa3
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Other | A1
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Other | A2
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Other | A3
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Other | Non-rated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 1,014,710