FEDERAL HOME LOAN BANK ADVANCES - LOANS PLEDGED (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
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	$ 1,127,811	$ 1,172,161
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	$ 315,289	300,681
Multi-family commercial 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		$ 14,913