INVESTMENTS - Summary of Investment Securities by Estimated Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Held-to-Maturity Amortized Cost
Amortized Cost	$ 49,631	$ 58,545
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	45,373	54,334
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	5,198,638	4,182,075
Available-for-Sale Market Value
Investment securities available-for-sale	4,953,023	3,971,932
One Year or Less [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	1,213
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	1,212
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	34,196
Available-for-Sale Market Value
Investment securities available-for-sale	34,132
After One Year Through Five Years [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	14,290
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	14,202
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	95,609
Available-for-Sale Market Value
Investment securities available-for-sale	87,628
After Five Years Through Ten Years [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	0
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	0
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	235,436
Available-for-Sale Market Value
Investment securities available-for-sale	210,923
After Ten Years [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	1,355
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	1,167
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	618,379
Available-for-Sale Market Value
Investment securities available-for-sale	554,733
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	2,008,226	1,607,916
Available-for-Sale Market Value
Investment securities available-for-sale	1,928,587	1,549,414
Commercial Mortgage Backed Securities [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	26,927	27,373
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	23,459	23,981
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	441,285	394,129
Available-for-Sale Market Value
Investment securities available-for-sale	425,644	381,600
Collateralized Mortgage Backed Securities [Member]
Held-to-Maturity Amortized Cost
Amortized Cost	5,846	6,088
Held-to-Maturity Market Value
Debt Securities, Held-to-maturity, Fair Value	5,333	5,589
Available-for-Sale Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost	1,096,428	741,819
Available-for-Sale Market Value
Investment securities available-for-sale	1,056,635	709,237
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	669,079	568,366
Available-for-Sale Market Value
Investment securities available-for-sale	$ 654,741	$ 556,544