8. STOCK- BASED COMPENSATION - Weighted average assumptions (Details) - $ / shares	3 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Stock-based compensation
Weighted average fair value per underlying share of options granted (in dollars per share)	$ 1.17	$ 1.89
Employee Consultants And Directors Stock Options
Stock-based compensation
Risk-free interest rate (as a percent)	1.26%	1.52%
Expected life	5 years	5 years
Volatility (as a percent)	34.80%	38.00%
Employee stock purchase plan
Stock-based compensation
Risk-free interest rate (as a percent)	0.38%	0.09%
Expected life	6 months	6 months
Volatility (as a percent)	39.60%	26.30%