Quarterly report pursuant to Section 13 or 15(d)

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

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Description of Stock Plans - Exercise Price for Options Outstanding and Options Exercisable (Detail) - Jun. 30, 2015 - $ / shares
Total
Employee Stock Ownership Plan E S O P Disclosures [Line Items]  
Options Outstanding, Number of Shares (in shares) 5,533,225
Options Exercisable, Number of Shares (in shares) 2,037,196
$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) 8,065
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 0.24
Options Outstanding, Weighted Average Remaining Life (Years) 4 years 8 months 27 days
Options Exercisable, Number of Shares (in 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) 237,594
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 0.65
Options Outstanding, Weighted Average Remaining Life (Years) 6 years 11 months 16 days
Options Exercisable, Number of Shares (in shares) 169,150
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) 153,776
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 2.40
Options Outstanding, Weighted Average Remaining Life (Years) 2 years 7 months 2 days
Options Exercisable, Number of Shares (in 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) 660,033
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 2.69
Options Outstanding, Weighted Average Remaining Life (Years) 8 years 3 months 29 days
Options Exercisable, Number of Shares (in shares) 354,926
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 2.69
$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) 2,179,742
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 3.93
Options Outstanding, Weighted Average Remaining Life (Years) 8 years 8 months 23 days
Options Exercisable, Number of Shares (in shares) 386,032
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) 1,764,015
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 4.21
Options Outstanding, Weighted Average Remaining Life (Years) 6 years 8 months 5 days
Options Exercisable, Number of Shares (in shares) 500,248
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 4.29
$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) 60,000
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 4.65
Options Outstanding, Weighted Average Remaining Life (Years) 7 years 8 months 27 days
Options Exercisable, Number of Shares (in shares) 45,000
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) 470,000
Options Outstanding, Weighted Average Exercise Price (in usd per share) $ 16.32
Options Outstanding, Weighted Average Remaining Life (Years) 2 years 9 months 29 days
Options Exercisable, Number of Shares (in shares) 420,000
Options Exercisable, Weighted Average Exercise Price (in usd per share) $ 17.56