8. STOCK- BASED COMPENSATION - Options outstanding by exercise price (Details) - $ / shares	3 Months Ended
	Jun. 30, 2016	Mar. 31, 2016
Options outstanding by exercise price
Exercise Price (in dollars per share)	$ 5.05	$ 5.08
Number of Shares Underlying Options Outstanding (in shares)	7,763,994
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.05
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 7 days
Options Exercisable, Number Vested and Exercisable (in shares)	5,417,275
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.03
$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)	885,004
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 3.17
Options Outstanding, Weighted Average Remaining Contractual Life	4 years 10 months 2 days
Options Exercisable, Number Vested and Exercisable (in shares)	576,194
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 3.04
$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)	1,269,559
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 3.79
Options Outstanding, Weighted Average Remaining Contractual Life	3 years 8 months 23 days
Options Exercisable, Number Vested and Exercisable (in shares)	1,108,969
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 3.82
$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)	934,778
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 4.41
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 6 months
Options Exercisable, Number Vested and Exercisable (in shares)	778,140
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 4.40
$4.90 - $4.98
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)	$ 4.98
Number of Shares Underlying Options Outstanding (in shares)	793,963
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 4.95
Options Outstanding, Weighted Average Remaining Contractual Life	7 years 7 months 28 days
Options Exercisable, Number Vested and Exercisable (in shares)	327,028
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 4.91
$5.13 - $5.34
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)	$ 5.34
Number of Shares Underlying Options Outstanding (in shares)	625,513
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.23
Options Outstanding, Weighted Average Remaining Contractual Life	8 years 3 months
Options Exercisable, Number Vested and Exercisable (in shares)	90,829
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.22
$5.50
Options outstanding by exercise price
Exercise Price (in dollars per share)	$ 5.50
Number of Shares Underlying Options Outstanding (in shares)	782,833
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.50
Options Outstanding, Weighted Average Remaining Contractual Life	4 months 17 days
Options Exercisable, Number Vested and Exercisable (in shares)	782,833
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.50
$5.59 - $6.00
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	5.59
Exercise Price, high end of range (in dollars per share)	$ 6.00
Number of Shares Underlying Options Outstanding (in shares)	899,830
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.77
Options Outstanding, Weighted Average Remaining Contractual Life	4 years 11 months 27 days
Options Exercisable, Number Vested and Exercisable (in shares)	568,526
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.80
$6.28 - $6.63
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	6.28
Exercise Price, high end of range (in dollars per share)	$ 6.63
Number of Shares Underlying Options Outstanding (in shares)	807,758
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 6.48
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 9 months 29 days
Options Exercisable, Number Vested and Exercisable (in shares)	645,179
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 6.47
$6.82 - $7.00
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	6.82
Exercise Price, high end of range (in dollars per share)	$ 7.00
Number of Shares Underlying Options Outstanding (in shares)	651,376
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 6.90
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 6 months 4 days
Options Exercisable, Number Vested and Exercisable (in shares)	426,197
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 6.91
$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	4 years 7 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