FEDERAL HOME LOAN BANK ADVANCES - LOANS PLEDGED (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
First lien, single family residential real estate
Real estate loans pledged to collateralize advances and letters of credit with the FHLB
Real estate loans pledged to collateralize advances and letters of credit with FHLB	$ 1,121,052	$ 1,123,402
Home equity lines of credit
Real estate loans pledged to collateralize advances and letters of credit with the FHLB
Real estate loans pledged to collateralize advances and letters of credit with FHLB	$ 317,751	$ 320,649

Amount of the collateral pledged in support of federal home loan bank advances outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant