5. FINANCIAL INSTRUMENTS - Available for sale investments (Details) - USD ($)	9 Months Ended
	Dec. 31, 2015	Mar. 31, 2015
Available-for-sale investments
Cost	$ 34,917,000
Fair Value	$ 34,870,000
Other information
Maximum maturity period of investment portfolio	3 years
Deferred tax asset related to unrecognized gains and losses on short-term and long-term investments	$ 17,000
Deferred tax liability related to unrecognized gains and losses on short-term and long-term investments		$ 11,000
Short-term investments
Available-for-sale investments
Cost	19,391,000	22,182,000
Gross Unrealized Gains	5,000	19,000
Gross Unrealized Losses	(15,000)
Fair Value	19,381,000	22,201,000
Short-term investments | State and municipal obligations
Available-for-sale investments
Cost	1,021,000	6,810,000
Gross Unrealized Gains	2,000
Fair Value	1,023,000	6,810,000
Short-term investments | Corporate notes
Available-for-sale investments
Cost	3,425,000	7,366,000
Gross Unrealized Gains		10,000
Gross Unrealized Losses	(6,000)
Fair Value	3,419,000	7,376,000
Short-term investments | Certificates of deposits
Available-for-sale investments
Cost	9,250,000	7,000,000
Gross Unrealized Gains	3,000	9,000
Gross Unrealized Losses	(5,000)
Fair Value	9,248,000	7,009,000
Short-term investments | International government obligations
Available-for-sale investments
Cost	2,692,000
Gross Unrealized Losses	(2,000)
Fair Value	2,690,000
Short-term investments | Agency bonds
Available-for-sale investments
Cost	3,003,000	1,006,000
Gross Unrealized Losses	(2,000)
Fair Value	3,001,000	1,006,000
Long-term investment
Available-for-sale investments
Cost	15,526,000	21,722,000
Gross Unrealized Gains	2,000	32,000
Gross Unrealized Losses	(39,000)	(14,000)
Fair Value	15,489,000	21,740,000
Long-term investment | State and municipal obligations
Available-for-sale investments
Cost		1,053,000
Gross Unrealized Gains		4,000
Fair Value		1,057,000
Long-term investment | Corporate notes
Available-for-sale investments
Cost	2,276,000	4,232,000
Gross Unrealized Losses	(10,000)	(10,000)
Fair Value	2,266,000	4,222,000
Long-term investment | Certificates of deposits
Available-for-sale investments
Cost	12,250,000	9,750,000
Gross Unrealized Gains	2,000	24,000
Gross Unrealized Losses	(29,000)	(1,000)
Fair Value	12,223,000	9,773,000
Long-term investment | International government obligations
Available-for-sale investments
Cost		2,684,000
Gross Unrealized Losses		(1,000)
Fair Value		2,683,000
Long-term investment | Agency bonds
Available-for-sale investments
Cost	1,000,000	4,003,000
Gross Unrealized Gains		4,000
Gross Unrealized Losses		(2,000)
Fair Value	$ 1,000,000	$ 4,005,000