Stockholders' Equity - Significant Ranges of Outstanding and Exercisable Options (Detail) (USD $)	12 Months Ended
	Sep. 30, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Options Outstanding	2,334,326
Weighted Average Remaining Contractual Life (in Years)	5 years 5 months 16 days
Weighted Average Exercise Price	$ 4.11
Number of Exercisable Options	1,878,695
Weighted Average Exercise Price of Exercisable Options	$ 3.94
Number of Unvested Options	455,631
$ 0.09 to $0.79 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	$ 0.09
Range of Exercise Prices, Upper Range	$ 0.79
Number of Options Outstanding	336,762
Weighted Average Remaining Contractual Life (in Years)	5 years 2 months 27 days
Weighted Average Exercise Price	$ 0.73
Number of Exercisable Options	336,762
Weighted Average Exercise Price of Exercisable Options	$ 0.73
$ 0.80 to $1.10 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	$ 0.80
Range of Exercise Prices, Upper Range	$ 1.10
Number of Options Outstanding	350,000
Weighted Average Remaining Contractual Life (in Years)	1 year 4 months 21 days
Weighted Average Exercise Price	$ 0.93
Number of Exercisable Options	350,000
Weighted Average Exercise Price of Exercisable Options	$ 0.93
$ 2.34 to $2.60 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	$ 2.34
Range of Exercise Prices, Upper Range	$ 2.60
Number of Options Outstanding	726,421
Weighted Average Remaining Contractual Life (in Years)	6 years 7 months 6 days
Weighted Average Exercise Price	$ 2.52
Number of Exercisable Options	491,671
Weighted Average Exercise Price of Exercisable Options	$ 2.54
Number of Unvested Options	234,750
$ 3.33 to $9.97 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	$ 3.33
Range of Exercise Prices, Upper Range	$ 9.97
Number of Options Outstanding	635,000
Weighted Average Remaining Contractual Life (in Years)	5 years 8 months 27 days
Weighted Average Exercise Price	$ 6.33
Number of Exercisable Options	501,023
Weighted Average Exercise Price of Exercisable Options	$ 6.74
Number of Unvested Options	133,977
$11.05 to $11.68 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	$ 11.05
Range of Exercise Prices, Upper Range	$ 11.68
Number of Options Outstanding	286,143
Weighted Average Remaining Contractual Life (in Years)	7 years 1 month 24 days
Weighted Average Exercise Price	$ 11.08
Number of Exercisable Options	199,239
Weighted Average Exercise Price of Exercisable Options	$ 11.08
Number of Unvested Options	86,904