SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Minimum period of past due loans to be placed on non accrual	30 days
Impairments of loan held for investment	$ 0	$ 0	$ 0
Furniture, fixtures and equipment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Useful life	15 years
Minimum | Accounting Standards Update 2016-13 | Subsequent event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Allowance for credit loss				$ 4,800,000
Allowance for credit loss, percent of total commitment balance				0.25%
Maximum | Accounting Standards Update 2016-13 | Subsequent event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Allowance for credit loss				$ 6,700,000
Allowance for credit loss, percent of total commitment balance				0.35%
Maximum | Furniture, fixtures and equipment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Useful life	40 years