FAIR VALUE OF FINANCIAL INSTRUMENTS: (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Mar. 31, 2020
Fair value of assets and liabilities
Other current assets	$ 24,560	$ 32,666
Fair value measurements on recurring basis | Total
Fair value of assets and liabilities
Other current assets	14,793
Total assets	14,793
Fair value measurements on recurring basis | Total | Level 1
Fair value of assets and liabilities
Other current assets	14,793
Total assets	14,793
Fair value measurements on recurring basis | Total | Level 2
Fair value of assets and liabilities
Other current assets	0
Total assets	0
Fair value measurements on recurring basis | Total | Level 3
Fair value of assets and liabilities
Other current assets	0
Total assets	$ 0