OTHER ACCRUED EXPENSES: (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018
Other Accrued Expenses [Abstract].
Liabilities of non-qualified retirement plan	$ 14,344	$ 13,551
Other accrued expenses	44,594	42,314
Other accrued expenses	$ 58,938	$ 55,865