Annual report pursuant to Section 13 and 15(d)

Description of Stock Plans - Exercise Price for Options Outstanding and Options Exercisable (Detail)

v3.19.1
Description of Stock Plans - Exercise Price for Options Outstanding and Options Exercisable (Detail)
 12 Months Ended
Mar. 31, 2019
$ / shares
shares
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Options Outstanding (in shares) | shares 9,128,885
Options Exercisable (in shares) | shares 5,800,564
$0.00 - 0.50  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit (in dollars per share) $ 0
Range of Exercise Price, upper limit (in dollars per share) $ 0.50
Options Outstanding (in shares) | shares 6,204
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 0.24
Weighted-Average Remaining Life (Years) 11 months 25 days
Options Exercisable (in shares) | shares 6,204
Options Exercisable, Weighted Average Exercise Price (in dollars per share) $ 0.24
$0.51 - 1.00  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit (in dollars per share) 0.51
Range of Exercise Price, upper limit (in dollars per share) $ 1.00
Options Outstanding (in shares) | shares 2,401,184
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 0.73
Weighted-Average Remaining Life (Years) 7 years 6 months 29 days
Options Exercisable (in shares) | shares 1,334,293
Options Exercisable, Weighted Average Exercise Price (in dollars per share) $ 0.73
$1.01 - 1.50  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit (in dollars per share) 1.01
Range of Exercise Price, upper limit (in dollars per share) $ 1.5
Options Outstanding (in shares) | shares 2,507,881
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 1.28
Weighted-Average Remaining Life (Years) 7 years 4 months 10 days
Options Exercisable (in shares) | shares 1,665,100
Options Exercisable, Weighted Average Exercise Price (in dollars per share) $ 1.27
$1.51 - 2.00  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit (in dollars per share) 1.51
Range of Exercise Price, upper limit (in dollars per share) $ 2
Options Outstanding (in shares) | shares 1,376,044
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 1.65
Weighted-Average Remaining Life (Years) 8 years 10 months 16 days
Options Exercisable (in shares) | shares 465,512
Options Exercisable, Weighted Average Exercise Price (in dollars per share) $ 1.62
$2.01 - 2.50  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit (in dollars per share) 2.01
Range of Exercise Price, upper limit (in dollars per share) $ 2.50
Options Outstanding (in shares) | shares 688,072
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 2.20
Weighted-Average Remaining Life (Years) 9 years 21 days
Options Exercisable (in shares) | shares 179,955
Options Exercisable, Weighted Average Exercise Price (in dollars per share) $ 2.17
$2.51 - 3.00  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit (in dollars per share) 2.51
Range of Exercise Price, upper limit (in dollars per share) $ 3.00
Options Outstanding (in shares) | shares 769,000
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 2.61
Weighted-Average Remaining Life (Years) 5 years 3 months 22 days
Options Exercisable (in shares) | shares 769,000
Options Exercisable, Weighted Average Exercise Price (in dollars per share) $ 2.61
$3.51 - 4.00  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit (in dollars per share) 3.51
Range of Exercise Price, upper limit (in dollars per share) $ 4.00
Options Outstanding (in shares) | shares 717,500
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 3.96
Weighted-Average Remaining Life (Years) 5 years 6 months 13 days
Options Exercisable (in shares) | shares 717,500
Options Exercisable, Weighted Average Exercise Price (in dollars per share) $ 3.96
$4.01 - 4.50  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit (in dollars per share) 4.01
Range of Exercise Price, upper limit (in dollars per share) $ 4.50
Options Outstanding (in shares) | shares 553,000
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 4.14
Weighted-Average Remaining Life (Years) 5 years 7 months 7 days
Options Exercisable (in shares) | shares 553,000
Options Exercisable, Weighted Average Exercise Price (in dollars per share) $ 4.14
$4.51 - 5.00  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit (in dollars per share) 4.51
Range of Exercise Price, upper limit (in dollars per share) $ 5.00
Options Outstanding (in shares) | shares 60,000
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 4.65
Weighted-Average Remaining Life (Years) 3 years 11 months 27 days
Options Exercisable (in shares) | shares 60,000
Options Exercisable, Weighted Average Exercise Price (in dollars per share) $ 4.65
$5.01 and over  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Exercise Price (in dollars per share) $ 5.0100
Options Outstanding (in shares) | shares 50,000
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 5.89
Weighted-Average Remaining Life (Years) 5 years 5 months 11 days
Options Exercisable (in shares) | shares 50,000
Options Exercisable, Weighted Average Exercise Price (in dollars per share) $ 5.89