OFF BALANCE SHEET RISKS, COMMITMENTS AND CONTINGENT LIABILITIES (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Commitments and letters of credit
Loan commitment, line credit	$ 1,644,120	$ 1,709,869
Unused warehouse lines of credit
Commitments and letters of credit
Loan commitment, line credit	490,213	591,305
Unused home equity lines of credit
Commitments and letters of credit
Loan commitment, line credit	380,012	377,277
Unused loan commitments - other
Commitments and letters of credit
Loan commitment, line credit	752,577	720,645
Standby letters of credit
Commitments and letters of credit
Loan commitment, line credit	11,318	10,642
FHLB letters of credit
Commitments and letters of credit
Loan commitment, line credit	$ 10,000	$ 10,000