11. STOCK-BASED COMPENSATION - Options outstanding by exercise price (Details) - $ / shares	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Options outstanding by exercise price
Exercise Price (in dollars per share)	$ 6.07	$ 6.17	$ 6.17	$ 5.77
Number of Shares Underlying Options Outstanding (in shares)	8,590,675
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 6.07
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 4 months 20 days
Options Exercisable, Number Vested and Exercisable (in shares)	5,499,074
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.86
$3.40 - $4.81
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	3.40
Exercise Price, high end of range (in dollars per share)	$ 4.81
Number of Shares Underlying Options Outstanding (in shares)	1,013,655
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 4.12
Options Outstanding, Weighted Average Remaining Contractual Life	3 years 6 months 29 days
Options Exercisable, Number Vested and Exercisable (in shares)	822,845
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 4.04
$4.98 - $4.99
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	4.98
Exercise Price, high end of range (in dollars per share)	$ 4.99
Number of Shares Underlying Options Outstanding (in shares)	1,050,501
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 4.99
Options Outstanding, Weighted Average Remaining Contractual Life	3 years 9 months 25 days
Options Exercisable, Number Vested and Exercisable (in shares)	1,050,501
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 4.99
$5.13 - $5.58
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)	$ 5.58
Number of Shares Underlying Options Outstanding (in shares)	1,410,456
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.42
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 4 months 13 days
Options Exercisable, Number Vested and Exercisable (in shares)	630,915
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.24
$5.59 - $5.83
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)	$ 5.83
Number of Shares Underlying Options Outstanding (in shares)	1,167,427
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.76
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 6 months 25 days
Options Exercisable, Number Vested and Exercisable (in shares)	535,873
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.70
$5.91 - $6.70
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	5.91
Exercise Price, high end of range (in dollars per share)	$ 6.70
Number of Shares Underlying Options Outstanding (in shares)	1,431,119
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 6.43
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 5 months 8 days
Options Exercisable, Number Vested and Exercisable (in shares)	828,589
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 6.36
$6.86 - $7.26
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	6.86
Exercise Price, high end of range (in dollars per share)	$ 7.26
Number of Shares Underlying Options Outstanding (in shares)	985,648
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 7.08
Options Outstanding, Weighted Average Remaining Contractual Life	4 years 18 days
Options Exercisable, Number Vested and Exercisable (in shares)	985,648
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 7.08
$7.40 - $7.88
Options outstanding by exercise price
Exercise Price, low end of range (in dollars per share)	7.40
Exercise Price, high end of range (in dollars per share)	$ 7.88
Number of Shares Underlying Options Outstanding (in shares)	726,606
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 7.61
Options Outstanding, Weighted Average Remaining Contractual Life	7 years 8 months 8 days
Options Exercisable, Number Vested and Exercisable (in shares)	398,243
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 7.63
$8.06
Options outstanding by exercise price
Exercise Price (in dollars per share)	$ 8.06
Number of Shares Underlying Options Outstanding (in shares)	157,210
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 8.06
Options Outstanding, Weighted Average Remaining Contractual Life	7 years 10 months 6 days
Options Exercisable, Number Vested and Exercisable (in shares)	78,604
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 8.06
$8.09
Options outstanding by exercise price
Exercise Price (in dollars per share)	$ 8.09
Number of Shares Underlying Options Outstanding (in shares)	82,160
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 8.09
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 9 months 29 days
Options Exercisable, Number Vested and Exercisable (in shares)	82,160
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 8.09
$8.30
Options outstanding by exercise price
Exercise Price (in dollars per share)	$ 8.30
Number of Shares Underlying Options Outstanding (in shares)	565,893
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 8.30
Options Outstanding, Weighted Average Remaining Contractual Life	7 years 3 months 3 days
Options Exercisable, Number Vested and Exercisable (in shares)	85,696
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 8.30