9. STOCK- BASED COMPENSATION - Stock options activities (Details) - USD ($)	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
STOCK- BASED COMPENSATION
Shares available for grant, Beginning	6,432,063	6,213,943	5,585,500
Options reserved (in shares)	1,085,818	1,156,419	1,377,699
Terminated plan (in shares)	(705,699)
Granted (in shares)	(1,362,798)	(969,913)	(791,903)
Forfeited (in shares)	14,801	31,614	42,647
Shares available for grant, Ending	5,464,185	6,432,063	6,213,943
Number of Shares Underlying Options Outstanding
Balance at the beginning of the period (in shares)	7,625,705	6,774,151	6,143,980
Granted (in shares)	1,362,798	969,913	791,903
Exercised (in shares)	(391,039)	(76,745)	(119,085)
Forfeited (in shares)	(974,634)	(41,614)	(42,647)
Balance at the end of the period (in shares)	7,622,830	7,625,705	6,774,151
Options vested and exercisable (in shares)	4,731,902
Options vested and expected to vest (in shares)	7,569,918
Weighted Average Remaining Contractual Life
Options vested and exercisable	4 years
Options vested and expected to vest	5 years 8 months 16 days
Weighted Average Exercise Price
Balance at the beginning of the period (in dollars per share)	$ 5.08	$ 5.16	$ 5.13
Granted (in dollars per share)	5.14	4.42	5.20
Exercised (in dollars per share)	3.96	4.19	3.88
Forfeited (in dollars per share)	5.53	4.82	5.49
Balance at the end of the period (in dollars per share)	5.09	$ 5.08	$ 5.16
Options vested and exercisable (in dollars per share)	5.04
Options vested and expected to vest (in dollars per share)	$ 5.09
Intrinsic Value
Exercised (in dollars)	$ 855,160	$ 46,977	$ 262,253
Options vested and exercisable (in dollars)	17,365,055
Options vested and expected to vest (in dollars)	$ 27,412,888