Summary of Significant Accounting Policies and Select Balance Sheet Information - Amortized Cost and Fair Value of Available-for-Sale Debt Securities by Contractual Maturity (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014
Amortized cost
Debt securities due within one year	$ 1,483
Debt securities due within one to five years	10,872
Debt securities due within five years or more	5,990
Total	18,345
Fair value
Debt securities due within one year	1,490
Debt securities due within one to five years	10,864
Debt securities due within five years or more	5,959
Total	$ 18,313