9. STOCK- BASED COMPENSATION - Options outstanding by exercise price (Details) - $ / shares	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Options outstanding by exercise price
Exercise Price (in dollars per share)	$ 5.09	$ 5.08	$ 5.16	$ 5.13
Number of Shares Underlying Options Outstanding (in shares)	7,622,830
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.09
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 8 months 23 days
Options Exercisable, Number Vested and Exercisable (in shares)	4,731,902
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.04
$2.43 - $3.40
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	2.43
Exercise Price, high end of range (in dollars per share)	$ 3.40
Number of Shares Underlying Options Outstanding (in shares)	789,595
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 3.22
Options Outstanding, Weighted Average Remaining Contractual Life	4 years 4 months 21 days
Options Exercisable, Number Vested and Exercisable (in shares)	558,137
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 3.14
$3.43 - $4.00
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	3.43
Exercise Price, high end of range (in dollars per share)	$ 4.00
Number of Shares Underlying Options Outstanding (in shares)	1,157,919
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 3.80
Options Outstanding, Weighted Average Remaining Contractual Life	3 years 15 days
Options Exercisable, Number Vested and Exercisable (in shares)	1,042,275
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 3.83
$4.17 - $4.81
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	4.17
Exercise Price, high end of range (in dollars per share)	$ 4.81
Number of Shares Underlying Options Outstanding (in shares)	840,645
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 4.42
Options Outstanding, Weighted Average Remaining Contractual Life	4 years 11 months 1 day
Options Exercisable, Number Vested and Exercisable (in shares)	750,395
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 4.41
$4.90 - $4.99
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	4.90
Exercise Price, high end of range (in dollars per share)	$ 4.99
Number of Shares Underlying Options Outstanding (in shares)	1,424,681
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 4.97
Options Outstanding, Weighted Average Remaining Contractual Life	8 years 1 month 17 days
Options Exercisable, Number Vested and Exercisable (in shares)	293,928
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 4.91
$5.13 - $5.28
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	5.13
Exercise Price, high end of range (in dollars per share)	$ 5.28
Number of Shares Underlying Options Outstanding (in shares)	798,098
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.23
Options Outstanding, Weighted Average Remaining Contractual Life	8 years 22 days
Options Exercisable, Number Vested and Exercisable (in shares)	90,030
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.19
$5.34 - $6.00
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	5.34
Exercise Price, high end of range (in dollars per share)	$ 6.00
Number of Shares Underlying Options Outstanding (in shares)	768,984
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.75
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 3 months 7 days
Options Exercisable, Number Vested and Exercisable (in shares)	728,336
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.76
$6.16 - $6.54
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	6.16
Exercise Price, high end of range (in dollars per share)	$ 6.54
Number of Shares Underlying Options Outstanding (in shares)	887,513
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 6.35
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 3 months 18 days
Options Exercisable, Number Vested and Exercisable (in shares)	584,903
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 6.43
$6.61 - $6.86
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	6.61
Exercise Price, high end of range (in dollars per share)	$ 6.86
Number of Shares Underlying Options Outstanding (in shares)	635,822
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 6.78
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 11 months 1 day
Options Exercisable, Number Vested and Exercisable (in shares)	364,325
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 6.74
$7.00
Options outstanding by exercise price
Exercise Price (in dollars per share)	$ 7.00
Number of Shares Underlying Options Outstanding (in shares)	206,193
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 7.00
Options Outstanding, Weighted Average Remaining Contractual Life	3 years 4 months 2 days
Options Exercisable, Number Vested and Exercisable (in shares)	206,193
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 7.00
$9.20
Options outstanding by exercise price
Exercise Price (in dollars per share)	$ 9.20
Number of Shares Underlying Options Outstanding (in shares)	113,380
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 9.20
Options Outstanding, Weighted Average Remaining Contractual Life	3 years 10 months 2 days
Options Exercisable, Number Vested and Exercisable (in shares)	113,380
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 9.20