ACQUISITIONS AND DIVESTITURES - Narrative (Details)	1 Months Ended				12 Months Ended
	Aug. 31, 2020 USD ($)	Jul. 31, 2020 USD ($)	Apr. 30, 2020 USD ($) shares	Mar. 31, 2020 USD ($) numberOfBank	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Apr. 03, 2020 loan	Nov. 30, 2019 numberOfBank
Business Acquisition [Line Items]
Assets					$ 2,331,476,000	$ 1,944,114,000
Liabilities					2,091,993,000	1,732,178,000
Gains on acquisition and divestiture activity					17,640,000	0	$ 0
Berkeley County, WV
Business Acquisition [Line Items]
Branch locations held for sale, number | numberOfBank									3
Jefferson County, WV
Business Acquisition [Line Items]
Branch locations held for sale, number | numberOfBank									1
The First State Bank
Business Acquisition [Line Items]
Net asset discount				$ 33,200,000
Branch locations acquired, number | numberOfBank				3
Purchase consideration				$ 1,500,000
Other real estate owned, percent of book value				46.50%
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Financial Liabilities			$ 142,520,000	$ 139,960,000
Cash and securities acquired				37,000,000.0
Loans			60,653,000	83,514,000
Transaction cash consideration received from the FDIC			39,627,000	$ 39,600,000
Number of loans acquired | loan								934
Cash Flows Expected to be Collected			74,216,000
Non-Accretable Credit Adjustments			27,403,000
Accretable FMV Adjustments			13,563,000
Deal related costs					1,200,000
Intercoastal
Business Acquisition [Line Items]
Percentage of common interest acquired		47.00%
Preferred units acquired		$ 7,500,000
Gains on acquisition and divestiture activity		$ 3,300,000
Purchased credit impaired loans | The First State Bank
Business Acquisition [Line Items]
Cash Flows Expected to be Collected			61,981,000
Non-Accretable Credit Adjustments			24,842,000
Accretable FMV Adjustments			11,746,000
Purchased performing loans
Business Acquisition [Line Items]
Cash Flows Expected to be Collected			39,500,000
Purchased performing loans | The First State Bank
Business Acquisition [Line Items]
Cash Flows Expected to be Collected			10,257,000
Non-Accretable Credit Adjustments			2,561,000
Accretable FMV Adjustments			1,817,000
Held-for-sale
Business Acquisition [Line Items]
Loans						$ 42,916,000
Held-for-sale | Eastern Panhandle, West Virginia Branches
Business Acquisition [Line Items]
Deposits assumed			188,100,000
Loans			$ 36,800,000
Gain on sale of banking centers					9,600,000
Assets					0
Liabilities					$ 0
Paladin
Business Acquisition [Line Items]
Number of shares issued | shares			19,278
Grand Software
Business Acquisition [Line Items]
Payments for asset acquisitions	$ 1,000,000.0
Intangibles resulting from Chartwell acquisition	$ 1,300,000