INVESTMENTS - Summary of Investment Securities by Estimated Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Held-to-Maturity Amortized Cost
Amortized Cost	$ 71,595	$ 76,960
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	65,911	68,989
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	3,669,996	3,512,652
Available-for-Sale Market Value
Investment securities available-for-sale	3,422,595	3,183,776
One Year or Less [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	715
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	715
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	14,381
Available-for-Sale Market Value
Investment securities available-for-sale	13,280
After One Year Through Five Years [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	6,167
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	6,247
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	187,361
Available-for-Sale Market Value
Investment securities available-for-sale	168,726
After Five Years Through Ten Years [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	28,750
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	27,373
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	158,546
Available-for-Sale Market Value
Investment securities available-for-sale	135,062
After Ten Years [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	1,438
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	1,250
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	470,350
Available-for-Sale Market Value
Investment securities available-for-sale	398,077
Residential Mortgage Backed Securities [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	0	0
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	0	0
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	1,358,833	1,102,242
Available-for-Sale Market Value
Investment securities available-for-sale	1,292,360	998,542
Commercial Mortgage Backed Securities [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	28,176	30,444
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	24,507	25,990
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	311,509	382,727
Available-for-Sale Market Value
Investment securities available-for-sale	293,009	357,372
Collateralized Mortgage Backed Securities [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	6,349	7,007
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	5,819	6,219
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	605,089	620,315
Available-for-Sale Market Value
Investment securities available-for-sale	570,277	569,165
Asset-backed Securities [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	0	0
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	0	0
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	563,927	555,484
Available-for-Sale Market Value
Investment securities available-for-sale	$ 551,804	$ 534,103