OTHER ACCRUED EXPENSES: (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Mar. 31, 2018
Other Accrued Expenses [Abstract].
Liabilities of non-qualified retirement plan	$ 13,706	$ 13,551
Other accrued expenses	41,429	26,073
Other accrued expenses	$ 55,135	$ 39,624