INVESTMENT SECURITIES - Schedule of Maturities of Investment Securities Available-for-Sale and Held-to-Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Available for Sale, Amortized Cost
Within one year	$ 2,562	$ 0
After one year but within five years	80,148	83,014
After five years but within ten years	555,909	465,777
After ten years	4,119,580	4,285,759
Amortized Cost	4,758,199	4,834,550
Available for Sale, Fair Value
Within one year	2,465	0
After one year but within five years	75,722	77,499
After five years but within ten years	476,621	398,607
After ten years	3,531,651	3,616,954
Available-for-sale, fair value total	4,086,459	4,093,060
Held to Maturity, Amortized Cost
Within one year	231	731
After one year but within five years	9,015	9,530
After five years but within ten years	41,627	46,170
After ten years	1,043,935	1,055,198
Investment securities held-to-maturity, net	1,094,808	1,111,629
Held to Maturity, Fair Value
Within one year	230	732
After one year but within five years	8,998	9,476
After five years but within ten years	41,803	45,944
After ten years	984,825	983,952
Held-to-maturity, fair value total	$ 1,035,856	$ 1,040,104