FINANCIAL INSTRUMENTS: (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Mar. 31, 2012
Fair value of assets and liabilities
Other current assets	$ 58,990	$ 57,804
Other liabilities	4,354	4,455
Fair value measurements on recurring basis | Level 1
Fair value of assets and liabilities
Other current assets	13,854
Total assets	13,854
Other current liabilities	13,854
Total liabilities	13,854
Fair value measurements on recurring basis | Level 2
Fair value of assets and liabilities
Other liabilities	1,196
Total liabilities	1,196
Fair value measurements on recurring basis | Total fair value
Fair value of assets and liabilities
Other current assets	13,854
Total assets	13,854
Other current liabilities	13,854
Other liabilities	1,196
Total liabilities	$ 15,050