GOODWILL AND OTHER INTANGIBLE ASSETS - Intangible Assets and Goodwill (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Finite-Lived Intangible Assets, Net [Abstract]
Intangible assets, gross	$ 55,172	$ 53,366
Accumulated amortization	(30,382)	(28,313)
Total amortizing intangible assets	24,790	25,053
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Amount	60,246	56,614
Accumulated amortization	(30,382)	(28,313)
Net Carrying Amount	29,864	28,301
Goodwill, gross	363,436	363,436
Goodwill, Net	363,436	363,436
Intangible projects in process
Indefinite-lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets	5,074	3,248
Core deposit intangibles
Finite-Lived Intangible Assets, Net [Abstract]
Intangible assets, gross	29,038	29,038
Accumulated amortization	(20,943)	(20,181)
Total amortizing intangible assets	8,095	8,857
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Accumulated amortization	$ (20,943)	$ (20,181)
Core deposit intangibles | Weighted Average
Finite-Lived Intangible Assets, Net [Abstract]
Finite-lived intangible asset, useful life	5 years 3 months 18 days	5 years 6 months
Software intangibles
Finite-Lived Intangible Assets, Net [Abstract]
Intangible assets, gross	$ 12,228	$ 10,422
Accumulated amortization	(1,134)	(183)
Total amortizing intangible assets	11,094	10,239
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Accumulated amortization	$ (1,134)	$ (183)
Software intangibles | Weighted Average
Finite-Lived Intangible Assets, Net [Abstract]
Finite-lived intangible asset, useful life	4 years 1 month 6 days	4 years 9 months 18 days
Other identifiable intangibles
Finite-Lived Intangible Assets, Net [Abstract]
Intangible assets, gross	$ 13,906	$ 13,906
Accumulated amortization	(8,305)	(7,949)
Total amortizing intangible assets	5,601	5,957
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Accumulated amortization	$ (8,305)	$ (7,949)
Other identifiable intangibles | Weighted Average
Finite-Lived Intangible Assets, Net [Abstract]
Finite-lived intangible asset, useful life	7 years 6 months	7 years 8 months 12 days