Quarterly report pursuant to Section 13 or 15(d)

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

v3.8.0.1
Description of Stock Plans - Exercise Price for Options Outstanding and Options Exercisable (Details)
 6 Months Ended
Sep. 30, 2017
$ / shares
shares
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Options Outstanding, Number of Shares (in shares) | shares 9,825,633
Options Exercisable, Number of Shares (in shares) | shares 4,162,328
$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, Number of Shares (in shares) | shares 7,652
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 0.24
Options Outstanding, Weighted Average Remaining Life (Years) 2 years 5 months 23 days
Options Exercisable, Number of Shares (in shares) | shares 7,652
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, Number of Shares (in shares) | shares 3,359,407
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 0.73
Options Outstanding, Weighted Average Remaining Life (Years) 9 years 15 days
Options Exercisable, Number of Shares (in shares) | shares 438,141
Options Exercisable, Weighted Average Exercise Price (in dollars per share) $ 0.69
$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, Number of Shares (in shares) | shares 2,892,564
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 1.28
Options Outstanding, Weighted Average Remaining Life (Years) 8 years 8 months 12 days
Options Exercisable, Number of Shares (in shares) | shares 635,671
Options Exercisable, Weighted Average Exercise Price (in dollars per share) $ 1.24
$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, Number of Shares (in shares) | shares 206,333
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 1.51
Options Outstanding, Weighted Average Remaining Life (Years) 7 years 10 months 17 days
Options Exercisable, Number of Shares (in shares) | shares 114,973
Options Exercisable, Weighted Average Exercise Price (in dollars 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 (in dollars per share) 2.01
Range of exercise price, upper limit (in dollars per share) $ 2.50
Options Outstanding, Number of Shares (in shares) | shares 253,779
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 2.43
Options Outstanding, Weighted Average Remaining Life (Years) 3 years 3 months 29 days
Options Exercisable, Number of Shares (in shares) | shares 220,445
Options Exercisable, Weighted Average Exercise Price (in dollars 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 (in dollars per share) 2.51
Range of exercise price, upper limit (in dollars per share) $ 3.00
Options Outstanding, Number of Shares (in shares) | shares 891,532
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 2.62
Options Outstanding, Weighted Average Remaining Life (Years) 6 years 8 months 23 days
Options Exercisable, Number of Shares (in shares) | shares 773,778
Options Exercisable, Weighted Average Exercise Price (in dollars 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 (in dollars per share) 3.51
Range of exercise price, upper limit (in dollars per share) $ 4.00
Options Outstanding, Number of Shares (in shares) | shares 840,300
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 3.96
Options Outstanding, Weighted Average Remaining Life (Years) 7 years 7 days
Options Exercisable, Number of Shares (in shares) | shares 732,385
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, Number of Shares (in shares) | shares 844,066
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 4.14
Options Outstanding, Weighted Average Remaining Life (Years) 5 years 9 months 26 days
Options Exercisable, Number of Shares (in shares) | shares 721,369
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, Number of Shares (in shares) | shares 60,000
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 4.65
Options Outstanding, Weighted Average Remaining Life (Years) 5 years 5 months 27 days
Options Exercisable, Number of Shares (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) $ 5.01
Options Outstanding, Number of Shares (in shares) | shares 470,000
Options Outstanding, Weighted Average Exercise Price (in dollars per share) $ 16.32
Options Outstanding, Weighted Average Remaining Life (Years) 1 year 3 months 4 days
Options Exercisable, Number of Shares (in shares) | shares 457,914
Options Exercisable, Weighted Average Exercise Price (in dollars per share) $ 16.60