COMMITMENTS AND CONTINGENCIES, INCLUDING FINANCIAL INSTRUMENTS WITH OFF-BALANCE-SHEET RISK - Contingent Liabilities & Lease Commitments (Details)	3 Months Ended
	Mar. 31, 2018 USD ($) item	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Contingent Liabilities
Number of private investment funds under the Small Business Investment Company (SBIC) program | item	2
Unfunded commitments	$ 3,400,000		$ 3,800,000
Cumulative capital contributions	2,100,000		$ 1,600,000
Lease Commitments
Rent expense	$ 465,000	$ 513,000