INVESTMENTS - Summary of Held-To-Maturity and Available-For-Sale Investment Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Investment Holdings [Line Items]
Total	$ 82,372	$ 84,021
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	83	105
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(10,056)	(7,641)
Held-to-Maturity Market Value	72,399	76,485
Total	3,660,078	3,827,418
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	1,723	834
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(412,397)	(418,604)
Investment securities available-for-sale	3,249,404	3,409,648
U.S. Treasuries
Investment Holdings [Line Items]
Total	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	0
Held-to-Maturity Market Value	0	0
Total	37,327	37,312
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	0	0
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(4,480)	(4,616)
Investment securities available-for-sale	32,847	32,696
Securities of U.S. government agencies and corporations
Investment Holdings [Line Items]
Total	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	0
Held-to-Maturity Market Value	0	0
Total	81,080	80,382
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	0	0
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(13,213)	(13,914)
Investment securities available-for-sale	67,867	66,468
Residential Mortgage Backed Securities [Member]
Investment Holdings [Line Items]
Total	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	0
Held-to-Maturity Market Value	0	0
Total	720,755	747,478
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	91	47
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(95,822)	(97,462)
Investment securities available-for-sale	625,024	650,063
Commercial Mortgage Backed Securities [Member]
Investment Holdings [Line Items]
Total	34,151	35,363
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(4,837)	(4,114)
Held-to-Maturity Market Value	29,314	31,249
Total	639,464	676,934
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	0	2
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(47,869)	(47,374)
Investment securities available-for-sale	591,595	629,562
Collateralized Mortgage Backed Securities [Member]
Investment Holdings [Line Items]
Total	8,818	9,280
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(947)	(827)
Held-to-Maturity Market Value	7,871	8,453
Total	506,674	538,970
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	31	181
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(64,521)	(61,439)
Investment securities available-for-sale	442,184	477,712
Obligations of state and other political subdivisions
Investment Holdings [Line Items]
Total	8,153	8,128
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	83	105
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(334)	(201)
Held-to-Maturity Market Value	7,902	8,032
Total	827,645	832,066
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	1,601	565
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(120,731)	(124,168)
Investment securities available-for-sale	708,515	708,463
Asset-backed Securities [Member]
Investment Holdings [Line Items]
Total	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	0
Held-to-Maturity Market Value	0	0
Total	710,251	772,261
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	0	39
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(53,080)	(60,975)
Investment securities available-for-sale	657,171	711,325
Other securities
Investment Holdings [Line Items]
Total	31,250	31,250
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(3,938)	(2,499)
Held-to-Maturity Market Value	27,312	28,751
Total	136,882	142,015
Available for Sale Securities Gross Unrealized Gain Accumulated In Investments	0	0
Available for Sale Securities Gross Unrealized Loss Accumulated In Investments	(12,681)	(8,656)
Investment securities available-for-sale	$ 124,201	$ 133,359