GOODWILL AND OTHER INTANGIBLE ASSETS - Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated amortization and net amount of intangible assets
Amortization	$ (2,344,000)	$ (706,000)	$ (88,000)
Core deposit intangibles
Gross amount of intangible assets
Gross amount, beginning of year	8,952,000
Additions due to acquisitions		8,952,000
Gross amount, end of year	8,952,000	8,952,000
Accumulated amortization and net amount of intangible assets
Accumulated amortization, beginning of year	(618,000)
Amortization	(2,299,000)	(618,000)
Accumulated amortization, end of year	(2,917,000)	(618,000)
Net CDI, end of year	6,035,000	$ 8,334,000
Estimated future amortization expense
2020	1,700,000
2021	1,200,000
2022	893,000
2023	757,000
2024	$ 758,000
Weighted average original amortization period	7 years 3 months 18 days