Fair Value Measurements (Assets Measured at Fair Value on a Recurring Basis) (Details) (Fair Value, Measurements, Recurring, USD $) | Dec. 31, 2014 | Sep. 30, 2014 |
In Thousands, unless otherwise specified |
Estimate of Fair Value Measurement [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | $81,304 | $87,149 |
Estimate of Fair Value Measurement [Member] | Money market funds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 16,356 | 29,995 |
Estimate of Fair Value Measurement [Member] | Corporate bonds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 22,276 | 20,854 |
Estimate of Fair Value Measurement [Member] | Municipal bonds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 30,705 | 31,151 |
Estimate of Fair Value Measurement [Member] | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 6,751 | |
Estimate of Fair Value Measurement [Member] | Certificates of deposit | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 5,216 | 5,149 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 38,632 | 50,849 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 16,356 | 29,995 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate bonds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 22,276 | 20,854 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Municipal bonds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 0 | 0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 0 | |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Certificates of deposit | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 0 | 0 |
Significant Other Observable Inputs (Level 2) | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 42,672 | 36,300 |
Significant Other Observable Inputs (Level 2) | Money market funds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Corporate bonds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Municipal bonds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 30,705 | 31,151 |
Significant Other Observable Inputs (Level 2) | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 6,751 | |
Significant Other Observable Inputs (Level 2) | Certificates of deposit | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 5,216 | 5,149 |
Significant Unobservable Inputs (Level 3) | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Money market funds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Corporate bonds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Municipal bonds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | 0 | |
Significant Unobservable Inputs (Level 3) | Certificates of deposit | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets at fair value on a recurring basis | $0 | $0 |