SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2018 USD ($)	Sep. 30, 2018 USD ($) subsidary
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income		$ 0
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income	$ 486	$ 486
The Bank
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of wholly-owned non-bank subsidiaries | subsidary		6