9. STOCK- BASED COMPENSATION - Weighted average assumptions (Details) - $ / shares	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Stock-based compensation
Expected life	5 years
Dividend yield (as a percent)	0.00%
Weighted average fair value per underlying share of options granted (in dollars per share)	$ 1.52	$ 2.08	$ 2.73
Employee Consultants And Directors Stock Options
Stock-based compensation
Risk-free interest rate, low end of range (as a percent)	1.41%	1.47%	0.91%
Risk-free interest rate, high end of range (as a percent)	1.57%	1.70%	1.61%
Expected life	5 years	5 years	5 years
Volatility, low end of range (as a percent)	36.30%	40.40%	45.50%
Volatility, high end of range (as a percent)	38.00%	44.80%	48.40%
Employee stock purchase plan
Stock-based compensation
Risk-free interest rate, low end of range (as a percent)	0.09%		0.07%
Risk-free interest rate, high end of range (as a percent)	0.15%	0.05%	0.09%
Expected life	6 months	6 months	6 months
Volatility, low end of range (as a percent)	26.30%	30.80%	30.40%
Volatility, high end of range (as a percent)	27.90%	38.00%	32.80%