Summary of Significant Accounting Policies - Schedule of Available-for-Sale Securities, All of Which Have Maturities of Twelve Months or Less (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 53,400
Unrealized Losses	(44)
Fair Value	53,356
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,000
Unrealized Losses
Fair Value	3,000
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	50,400
Unrealized Losses	(44)
Fair Value	$ 50,356