INVESTMENT SECURITIES - Summary of Amortized Cost of Investment Securities Held to Maturity Aggregated by Credit Quality Indicator (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Schedule of Held-to-maturity Securities [Line Items]
Total	$ 1,995,733	$ 2,074,465
Aaa
Schedule of Held-to-maturity Securities [Line Items]
Total	999,020	1,107,845
Aa1
Schedule of Held-to-maturity Securities [Line Items]
Total	200,380	148,923
Aa2
Schedule of Held-to-maturity Securities [Line Items]
Total	177,970	184,341
Aa3
Schedule of Held-to-maturity Securities [Line Items]
Total	180,534	185,166
A1
Schedule of Held-to-maturity Securities [Line Items]
Total	59,635	65,665
A2
Schedule of Held-to-maturity Securities [Line Items]
Total	20,329	20,317
Non-rated
Schedule of Held-to-maturity Securities [Line Items]
Total	357,865	362,208
U.S. Government-sponsored agency securities
Schedule of Held-to-maturity Securities [Line Items]
Total	330,430	345,531
U.S. Government-sponsored agency securities | Aaa
Schedule of Held-to-maturity Securities [Line Items]
Total	330,430	345,531
U.S. Government-sponsored agency securities | Aa1
Schedule of Held-to-maturity Securities [Line Items]
Total	0	0
U.S. Government-sponsored agency securities | Aa2
Schedule of Held-to-maturity Securities [Line Items]
Total	0	0
U.S. Government-sponsored agency securities | Aa3
Schedule of Held-to-maturity Securities [Line Items]
Total	0	0
U.S. Government-sponsored agency securities | A1
Schedule of Held-to-maturity Securities [Line Items]
Total	0	0
U.S. Government-sponsored agency securities | A2
Schedule of Held-to-maturity Securities [Line Items]
Total	0	0
U.S. Government-sponsored agency securities | Non-rated
Schedule of Held-to-maturity Securities [Line Items]
Total	0	0
State and municipal
Schedule of Held-to-maturity Securities [Line Items]
Total	1,072,380	1,085,921
State and municipal | Aaa
Schedule of Held-to-maturity Securities [Line Items]
Total	75,667	120,801
State and municipal | Aa1
Schedule of Held-to-maturity Securities [Line Items]
Total	200,380	148,923
State and municipal | Aa2
Schedule of Held-to-maturity Securities [Line Items]
Total	177,970	184,341
State and municipal | Aa3
Schedule of Held-to-maturity Securities [Line Items]
Total	180,534	185,166
State and municipal | A1
Schedule of Held-to-maturity Securities [Line Items]
Total	59,635	65,665
State and municipal | A2
Schedule of Held-to-maturity Securities [Line Items]
Total	20,329	20,317
State and municipal | Non-rated
Schedule of Held-to-maturity Securities [Line Items]
Total	357,865	360,708
U.S. Government-sponsored mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Total	592,923	641,513
U.S. Government-sponsored mortgage-backed securities | Aaa
Schedule of Held-to-maturity Securities [Line Items]
Total	592,923	641,513
U.S. Government-sponsored mortgage-backed securities | Aa1
Schedule of Held-to-maturity Securities [Line Items]
Total	0	0
U.S. Government-sponsored mortgage-backed securities | Aa2
Schedule of Held-to-maturity Securities [Line Items]
Total	0	0
U.S. Government-sponsored mortgage-backed securities | Aa3
Schedule of Held-to-maturity Securities [Line Items]
Total	0	0
U.S. Government-sponsored mortgage-backed securities | A1
Schedule of Held-to-maturity Securities [Line Items]
Total	0	0
U.S. Government-sponsored mortgage-backed securities | A2
Schedule of Held-to-maturity Securities [Line Items]
Total	0	0
U.S. Government-sponsored mortgage-backed securities | Non-rated
Schedule of Held-to-maturity Securities [Line Items]
Total	$ 0	0
Foreign investment
Schedule of Held-to-maturity Securities [Line Items]
Total		1,500
Foreign investment | Aaa
Schedule of Held-to-maturity Securities [Line Items]
Total		0
Foreign investment | Aa1
Schedule of Held-to-maturity Securities [Line Items]
Total		0
Foreign investment | Aa2
Schedule of Held-to-maturity Securities [Line Items]
Total		0
Foreign investment | Aa3
Schedule of Held-to-maturity Securities [Line Items]
Total		0
Foreign investment | A1
Schedule of Held-to-maturity Securities [Line Items]
Total		0
Foreign investment | A2
Schedule of Held-to-maturity Securities [Line Items]
Total		0
Foreign investment | Non-rated
Schedule of Held-to-maturity Securities [Line Items]
Total		$ 1,500