Quarterly report pursuant to Section 13 or 15(d)

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

v3.7.0.1
Description of Stock Plans - Exercise Price for Options Outstanding and Options Exercisable (Detail)
 3 Months Ended
Jun. 30, 2017
$ / shares
shares
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Options Outstanding, Number of Shares (in shares) | shares 9,526,233
Options Exercisable, Number of Shares (in shares) | shares 3,699,003
$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 7,652
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 0.24
Options Outstanding, Weighted Average Remaining Life (Years) 2 years 8 months 27 days
Options Exercisable, Number of Shares (in shares) | shares 7,652
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 3,476,123
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 0.73
Options Outstanding, Weighted Average Remaining Life (Years) 9 years 3 months 22 days
Options Exercisable, Number of Shares (in shares) | shares 350,113
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 0.67
$1.01 - 1.50  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit 1.01
Range of Exercise Price, upper limit $ 1.5
Options Outstanding, Number of Shares (in shares) | shares 2,384,892
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 1.32
Options Outstanding, Weighted Average Remaining Life (Years) 8 years 8 months 23 days
Options Exercisable, Number of Shares (in shares) | shares 398,465
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 1.22
$1.51 - 2.00  
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Range of Exercise Price, lower limit 1.51
Range of Exercise Price, upper limit $ 2
Options Outstanding, Number of Shares (in shares) | shares 210,500
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 1.51
Options Outstanding, Weighted Average Remaining Life (Years) 8 years 4 months 6 days
Options Exercisable, Number of Shares (in shares) | shares 102,125
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 1.51
$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 253,779
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 2.43
Options Outstanding, Weighted Average Remaining Life (Years) 3 years 6 months 29 days
Options Exercisable, Number of Shares (in shares) | shares 203,779
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 2.42
$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 920,034
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 2.62
Options Outstanding, Weighted Average Remaining Life (Years) 6 years 11 months 19 days
Options Exercisable, Number of Shares (in shares) | shares 735,370
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 2.63
$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 895,854
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 3.96
Options Outstanding, Weighted Average Remaining Life (Years) 6 years 10 months 10 days
Options Exercisable, Number of Shares (in shares) | shares 700,046
Options Exercisable, Weighted Average Exercise Price (in usd 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 4.01
Range of Exercise Price, upper limit $ 4.50
Options Outstanding, Number of Shares (in shares) | shares 847,399
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 4.14
Options Outstanding, Weighted Average Remaining Life (Years) 6 years 2 months 5 days
Options Exercisable, Number of Shares (in shares) | shares 687,078
Options Exercisable, Weighted Average Exercise Price (in usd 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 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) 5 years 8 months 27 days
Options Exercisable, Number of Shares (in shares) | shares 60,000
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) 1 year 6 months 4 days
Options Exercisable, Number of Shares (in shares) | shares 454,375
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 16.68