OTHER ACCRUED EXPENSES: (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Other Accrued Expenses [Abstract].
Liabilities of non-qualified retirement plan	$ 14,886	$ 14,970
Short-term lease liabilities	8,550	0
PDP performance plan liability (see Note 7)	17,481	0
DPM consideration holdback (see Note 7)	4,123	0
Other miscellaneous accrued expenses	29,039	25,946
Other accrued expenses	$ 74,079	$ 40,916