INVESTMENT SECURITIES - Summary of Amortized Cost of Investment Securities Held to Maturity Aggregated by Credit Quality Indicator (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Schedule of Held-to-maturity Securities [Line Items]
Total	$ 1,873,196	$ 1,971,784
Aaa
Schedule of Held-to-maturity Securities [Line Items]
Total	903,354	977,729
Aa1
Schedule of Held-to-maturity Securities [Line Items]
Total	216,863	200,189
Aa2
Schedule of Held-to-maturity Securities [Line Items]
Total	148,671	172,127
Aa3
Schedule of Held-to-maturity Securities [Line Items]
Total	187,732	192,682
A1
Schedule of Held-to-maturity Securities [Line Items]
Total	59,622	59,631
A2
Schedule of Held-to-maturity Securities [Line Items]
Total	10,192	13,664
A3
Schedule of Held-to-maturity Securities [Line Items]
Total	10,156	6,670
Non-rated
Schedule of Held-to-maturity Securities [Line Items]
Total	336,606	349,092
U.S. Government-sponsored agency securities
Schedule of Held-to-maturity Securities [Line Items]
Total	308,998	324,643
U.S. Government-sponsored agency securities \| Aaa
Schedule of Held-to-maturity Securities [Line Items]
Total	308,998	324,643
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 \| A3
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	1,043,391	1,069,653
State and municipal \| Aaa
Schedule of Held-to-maturity Securities [Line Items]
Total	73,549	75,598
State and municipal \| Aa1
Schedule of Held-to-maturity Securities [Line Items]
Total	216,863	200,189
State and municipal \| Aa2
Schedule of Held-to-maturity Securities [Line Items]
Total	148,671	172,127
State and municipal \| Aa3
Schedule of Held-to-maturity Securities [Line Items]
Total	187,732	192,682
State and municipal \| A1
Schedule of Held-to-maturity Securities [Line Items]
Total	59,622	59,631
State and municipal \| A2
Schedule of Held-to-maturity Securities [Line Items]
Total	10,192	13,664
State and municipal \| A3
Schedule of Held-to-maturity Securities [Line Items]
Total	10,156	6,670
State and municipal \| Non-rated
Schedule of Held-to-maturity Securities [Line Items]
Total	336,606	349,092
U.S. Government-sponsored mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Total	520,807	577,488
U.S. Government-sponsored mortgage-backed securities \| Aaa
Schedule of Held-to-maturity Securities [Line Items]
Total	520,807	577,488
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 \| A3
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