GOODWILL AND INTANGIBLE ASSETS - Summary of Other Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 118,098	$ 118,098	$ 118,373
Accumulated Amortization	(28,411)	(28,411)	(22,456)
Total	89,687	89,687	95,917
Core deposits
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	95,711	95,711	95,711
Accumulated Amortization	(18,033)	(18,033)	(13,326)
Total	77,678	$ 77,678	$ 82,385
Amortization Period		10 years	10 years
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	17,561	$ 17,561	$ 17,561
Accumulated Amortization	(8,216)	(8,216)	(7,416)
Total	9,345	$ 9,345	$ 10,145
Customer relationships | Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization Period		7 years	7 years
Customer relationships | Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization Period		15 years	15 years
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	221	$ 221	$ 221
Accumulated Amortization	(168)	(168)	(146)
Total	53	$ 53	$ 75
Amortization Period		5 years	5 years
Loan servicing rights
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	4,605	$ 4,605	$ 4,880
Accumulated Amortization	(1,994)	(1,994)	(1,568)
Total	2,611	2,611	3,312
Impairment loss	$ 300	$ 400	$ 500
Loan servicing rights | Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization Period		10 years	10 years
Loan servicing rights | Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization Period		25 years	25 years