OTHER ACCRUED EXPENSES: (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017
Other Accrued Expenses [Abstract].
Accrued purchase consideration	$ 0	$ 5,880
Liabilities of non-qualified retirement plan	14,111	12,716
Other accrued expenses	39,888	41,265
Other accrued expenses	$ 53,999	$ 59,861