ACCOUNTING POLICIES (Narrative) (Details)			3 Months Ended
	Dec. 31, 2021 USD ($)		Mar. 31, 2022 USD ($) property	Mar. 31, 2021 USD ($)	Sep. 30, 2021	Dec. 31, 2020 USD ($)
Organization And Significant Accounting Policies [Line Items]
Number of branches | property			40
Cumulative effect adjustment	$ 411,881,000	[1]	$ 404,195,000	$ 397,986,000		$ 390,554,000
Net income			4,593,000	9,383,000
Salaries and benefits			9,625,000	$ 9,372,000
Securities available for sale, at fair value	271,332,000	[1]	271,626,000
Notes receivable	2,305,997,000		$ 2,393,669,000
Southern Trust Mortgage [Member]
Organization And Significant Accounting Policies [Line Items]
Notes receivable	8,500,000
Southern Trust Mortgage [Member]
Organization And Significant Accounting Policies [Line Items]
Payments to acquire equity method investments	$ 1,600,000
Common Stock | Southern Trust Mortgage [Member] | Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Organization And Significant Accounting Policies [Line Items]
Percentage of equity investment and preferred stock of STM					43.28%
Preferred Stock | Southern Trust Mortgage [Member]
Organization And Significant Accounting Policies [Line Items]
Percentage of equity investment and preferred stock of STM			100.00%
Preferred Stock | Southern Trust Mortgage [Member] | Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Organization And Significant Accounting Policies [Line Items]
Percentage of equity investment and preferred stock of STM					100.00%
Paycheck Protection Program Loans [Member]
Organization And Significant Accounting Policies [Line Items]
Financing receivable, allowance for credit loss			$ 0
Virginia [Member]
Organization And Significant Accounting Policies [Line Items]
Number of branches | property			35
Maryland
Organization And Significant Accounting Policies [Line Items]
Number of branches | property			5

[1] Derived from audited consolidated financial statements