SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Other Narrative (Details) $ / shares in Units, shares in Millions	1 Months Ended	12 Months Ended
	Aug. 31, 2020 USD ($)	Dec. 31, 2020 USD ($) segment investment method $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) shares	Jul. 31, 2020 USD ($)	Apr. 30, 2020 numberOfBank	Nov. 30, 2019 numberOfBank
Summary of Significant Accounting Policies [Line Items]
Branch locations acquired, number | numberOfBank						3
Number of equity method investments | investment		1
Period past due for loans to be considered as delinquent		90 days
Total valuation methods used on impaired loans | method		3
Total loans serviced for others		$ 2,900,000	$ 300,000
Other real estate		5,700,000	1,400,000
Marketing expense		1,096,000	$ 1,290,000	$ 1,141,000
Change in tax rate				$ 600,000
Deferred income tax valuation allowance		0
Liability for uncertain tax positions		0
Unrecognized tax benefits		$ 0
Number of reportable segments | segment		3
Stock Options
Summary of Significant Accounting Policies [Line Items]
Antidilutive securities (in shares) | shares		0.5	0.4	0.3
Grand Software
Summary of Significant Accounting Policies [Line Items]
Payments for asset acquisitions	$ 1,000,000.0
Berkeley County, WV
Summary of Significant Accounting Policies [Line Items]
Branch locations held for sale, number | numberOfBank							3
Jefferson County, WV
Summary of Significant Accounting Policies [Line Items]
Branch locations held for sale, number | numberOfBank							1
Minimum | Building and Leasehold Improvements
Summary of Significant Accounting Policies [Line Items]
Estimated useful lives		7 years
Minimum | Furniture, Fixtures And Equipment
Summary of Significant Accounting Policies [Line Items]
Estimated useful lives		3 years
Maximum | Building and Leasehold Improvements
Summary of Significant Accounting Policies [Line Items]
Estimated useful lives		40 years
Maximum | Furniture, Fixtures And Equipment
Summary of Significant Accounting Policies [Line Items]
Estimated useful lives		10 years
Subsidiary Bank
Summary of Significant Accounting Policies [Line Items]
FHLB stock		$ 2,800,000	$ 15,000,000.0
FHLB stock par value (in dollars per share) | $ / shares		$ 100	$ 100
Intercoastal
Summary of Significant Accounting Policies [Line Items]
Percentage of common interest acquired					47.00%
Preferred units acquired					$ 7,500,000