INVESTMENT SECURITIES - Schedule of Maturities of Investment Securities Available-for-Sale and Held-to-Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Available for Sale, Amortized Cost
Within one year	$ 23,742	$ 16,833
After one year but within five years	174,423	147,157
After five years but within ten years	462,611	487,921
After ten years	3,419,618	3,566,355
Amortized Cost	4,080,394	4,218,266
Available for Sale, Fair Value
Within one year	23,411	16,698
After one year but within five years	165,335	138,870
After five years but within ten years	403,623	409,908
After ten years	2,902,414	2,945,172
Fair value	3,494,783	3,510,648
Held to Maturity, Amortized Cost
Within one year	970	0
After one year but within five years	17,256	16,727
After five years but within ten years	61,882	51,671
After ten years	914,238	946,770
Past due held-to-maturity debt securities	994,346	1,015,168
Held to Maturity, Fair Value
Within one year	969	0
After one year but within five years	17,155	16,444
After five years but within ten years	60,749	50,451
After ten years	805,387	828,616
Fair value	$ 884,260	$ 895,511