OFF BALANCE SHEET RISKS, COMMITMENTS AND CONTINGENT LIABILITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Commitments and letters of credit
Loan commitment, line credit	$ 1,490,797	$ 1,513,860
Unused warehouse lines of credit
Commitments and letters of credit
Loan commitment, line credit	451,686	525,328
Unused home equity lines of credit
Commitments and letters of credit
Loan commitment, line credit	380,320	367,887
Unused loan commitments - other
Commitments and letters of credit
Loan commitment, line credit	641,978	598,002
Standby letters of credit
Commitments and letters of credit
Loan commitment, line credit	6,813	12,643
FHLB letters of credit
Commitments and letters of credit
Loan commitment, line credit	$ 10,000	$ 10,000