Marketable Securities - Summary of Future Maturities of Available-For-Sale Securities (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized cost, maturities Less than 12 months	$ 27,065
Available-for-sale securities, Fair value, maturities Less than 12 months	27,228
Available-for-sale securities, Amortized cost, maturities Greater than 12 months	0
Available-for-sale securities, Fair value, maturities Greater than 12 months	0
Common stock
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized cost, maturities Less than 12 months	197
Available-for-sale securities, Fair value, maturities Less than 12 months	360
Available-for-sale securities, Amortized cost, maturities Greater than 12 months	0
Available-for-sale securities, Fair value, maturities Greater than 12 months	0
Government and agency securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized cost, maturities Less than 12 months	26,868
Available-for-sale securities, Fair value, maturities Less than 12 months	26,868
Available-for-sale securities, Amortized cost, maturities Greater than 12 months	0
Available-for-sale securities, Fair value, maturities Greater than 12 months	$ 0