8. STOCK- BASED COMPENSATION - Stock options activities (Details)	3 Months Ended
	Jun. 30, 2016 USD ($) $ / shares shares
STOCK- BASED COMPENSATION
Shares available for grant, Beginning	6,432,063
Options reserved (in shares)	1,085,818
Granted (in shares)	(160,590)
Forfeited (in shares)	1,501
Shares available for grant, Ending	7,358,792
Number of Shares Underlying Options Outstanding
Balance at the beginning of the period (in shares)	7,625,705
Granted (in shares)	160,590
Exercised (in shares)	(20,200)
Forfeited (in shares)	(2,101)
Balance at the end of the period (in shares)	7,763,994
Options vested and exercisable (in shares)	5,417,275
Options vested and expected to vest (in shares)	7,719,468
Weighted Average Remaining Contractual Life
Options vested and exercisable	3 years 6 months 29 days
Options vested and expected to vest	5 years
Weighted Average Exercise Price
Balance at the beginning of the period (in dollars per share) | $ / shares	$ 5.08
Granted (in dollars per share) | $ / shares	3.60
Exercised (in dollars per share) | $ / shares	3.39
Forfeited (in dollars per share) | $ / shares	5.82
Balance at the end of the period (in dollars per share) | $ / shares	5.05
Options vested and exercisable (in dollars per share) | $ / shares	5.03
Options vested and expected to vest (in dollars per share) | $ / shares	$ 5.05
Intrinsic Value
Exercised (in dollars) | $	$ 10,208
Options vested and exercisable (in dollars) | $	1,043,486
Options vested and expected to vest (in dollars) | $	$ 1,365,215