GOODWILL AND INTANGIBLE ASSETS - Summary of Acquired Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 196,111	$ 131,565
Accumulated Amortization	70,173	59,591
Core deposit premiums
Finite-Lived Intangible Assets [Line Items]
Gross Amount	103,574	107,958
Accumulated Amortization	58,456	50,829
Referral relationships
Finite-Lived Intangible Assets [Line Items]
Gross Amount	88,651	22,351
Accumulated Amortization	10,943	8,149
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross Amount	2,734	1,094
Accumulated Amortization	612	456
Patent
Finite-Lived Intangible Assets [Line Items]
Gross Amount	420	0
Accumulated Amortization	0	0
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Amount	732	162
Accumulated Amortization	$ 162	$ 157