SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - (Details) - item	12 Months Ended
	Dec. 31, 2017	Jun. 30, 2017	Apr. 28, 2017	May 20, 2016
Cash Flows
Maximum maturity period of interest bearing deposits with other financial institutions	90 days
Securities
Number of components in which amount of impairment of securities is spilt	2
Cheviot Financial Corp.
Nature of Operations and Principles of Consolidation
Acquisition of outstanding common shares (as a percent)				100.00%
FCB Bancorp, Inc.
Nature of Operations and Principles of Consolidation
Acquisition of outstanding common shares (as a percent)		100.00%	100.00%