OFF BALANCE SHEET RISKS, COMMITMENTS AND CONTINGENT LIABILITIES (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Commitments and letters of credit
Loan commitment, line credit	$ 1,596,578	$ 1,513,860
Unused warehouse lines of credit
Commitments and letters of credit
Loan commitment, line credit	491,942	525,328
Unused home equity lines of credit
Commitments and letters of credit
Loan commitment, line credit	378,232	367,887
Unused loan commitments - other
Commitments and letters of credit
Loan commitment, line credit	703,759	598,002
Standby letters of credit
Commitments and letters of credit
Loan commitment, line credit	12,645	12,643
FHLB letters of credit
Commitments and letters of credit
Loan commitment, line credit	$ 10,000	$ 10,000