Quarterly report pursuant to Section 13 or 15(d)

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

v3.3.0.814
Description of Stock Plans - Exercise Price for Options Outstanding and Options Exercisable (Detail)
 6 Months Ended
Sep. 30, 2015
$ / shares
shares
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Options Outstanding, Number of Shares (in shares) | shares 5,993,975
Options Exercisable, Number of Shares (in shares) | shares 2,348,204
$0.00 - 0.50  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit $ 0
Range of Exercise Price, upper limit $ 0.50
Options Outstanding, Number of Shares (in shares) | shares 8,064
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 0.24
Options Outstanding, Weighted Average Remaining Life (Years) 4 years 5 months 27 days
Options Exercisable, Number of Shares (in shares) | shares 8,064
Options Exercisable, Weighted Average Exercise Price (in usd 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 0.51
Range of Exercise Price, upper limit $ 1.00
Options Outstanding, Number of Shares (in shares) | shares 176,060
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 0.65
Options Outstanding, Weighted Average Remaining Life (Years) 6 years 11 months 9 days
Options Exercisable, Number of Shares (in shares) | shares 179,996
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 0.64
$2.01 - 2.50  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit 2.01
Range of Exercise Price, upper limit $ 2.50
Options Outstanding, Number of Shares (in shares) | shares 253,776
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 2.43
Options Outstanding, Weighted Average Remaining Life (Years) 5 years 3 months 29 days
Options Exercisable, Number of Shares (in shares) | shares 153,776
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 2.40
$2.51 - 3.00  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit 2.51
Range of Exercise Price, upper limit $ 3.00
Options Outstanding, Number of Shares (in shares) | shares 1,313,710
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 2.62
Options Outstanding, Weighted Average Remaining Life (Years) 9 years
Options Exercisable, Number of Shares (in shares) | shares 396,543
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 2.66
$3.51 - 4.00  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit 3.51
Range of Exercise Price, upper limit $ 4.00
Options Outstanding, Number of Shares (in shares) | shares 2,028,860
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 3.93
Options Outstanding, Weighted Average Remaining Life (Years) 9 years 1 month 28 days
Options Exercisable, Number of Shares (in shares) | shares 505,709
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 3.95
$4.01 - 4.50  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit 4.01
Range of Exercise Price, upper limit $ 4.50
Options Outstanding, Number of Shares (in shares) | shares 1,683,505
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 4.20
Options Outstanding, Weighted Average Remaining Life (Years) 8 years 2 months 19 days
Options Exercisable, Number of Shares (in shares) | shares 621,616
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 4.24
$4.51 - 5.00  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit 4.51
Range of Exercise Price, upper limit $ 5.00
Options Outstanding, Number of Shares (in shares) | shares 60,000
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 4.65
Options Outstanding, Weighted Average Remaining Life (Years) 7 years 5 months 27 days
Options Exercisable, Number of Shares (in shares) | shares 50,000
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 4.65
$5.01 and over  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Exercise Price $ 5.01
Options Outstanding, Number of Shares (in shares) | shares 470,000
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 16.32
Options Outstanding, Weighted Average Remaining Life (Years) 3 years 3 months 4 days
Options Exercisable, Number of Shares (in shares) | shares 432,500
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 17.22