|
Fair Value (Details) (USD $)
In Thousands, unless otherwise specified |
Sep. 30, 2014
|
Dec. 31, 2013
|
|---|---|---|
|
U S Treasury Securities [Member]
|
||
| Fair Value | ||
| Investments at fair value | $ 2,029 | $ 2,085 |
|
U S Government Sponsored Enterprises Debt Securities [Member]
|
||
| Fair Value | ||
| Investments at fair value | 52,093 | 67,178 |
|
Corporate Bond Securities And Commercial Paper [Member]
|
||
| Fair Value | ||
| Investments at fair value | 94,036 | 133,458 |
|
Fair Value Measurements Recurring [Member] | Fair Value Inputs Level1 [Member]
|
||
| Fair Value | ||
| Investments at fair value | 8,754 | 9,059 |
|
Fair Value Measurements Recurring [Member] | Fair Value Inputs Level1 [Member] | Money Market Funds [Member]
|
||
| Fair Value | ||
| Investments at fair value | 8,754 | 9,059 |
|
Fair Value Measurements Recurring [Member] | Fair Value Inputs Level2 [Member]
|
||
| Fair Value | ||
| Investments at fair value | 148,158 | 202,721 |
|
Fair Value Measurements Recurring [Member] | Fair Value Inputs Level2 [Member] | U S Treasury Securities [Member]
|
||
| Fair Value | ||
| Investments at fair value | 2,029 | 2,085 |
|
Fair Value Measurements Recurring [Member] | Fair Value Inputs Level2 [Member] | U S Government Sponsored Enterprises Debt Securities [Member]
|
||
| Fair Value | ||
| Investments at fair value | 52,093 | 67,178 |
|
Fair Value Measurements Recurring [Member] | Fair Value Inputs Level2 [Member] | Corporate Bond Securities And Commercial Paper [Member]
|
||
| Fair Value | ||
| Investments at fair value | 94,036 | 133,458 |
|
Fair Value Measurements Recurring [Member] | Estimate Of Fair Value Fair Value Disclosure [Member]
|
||
| Fair Value | ||
| Investments at fair value | 156,912 | 211,780 |
|
Fair Value Measurements Recurring [Member] | Estimate Of Fair Value Fair Value Disclosure [Member] | Money Market Funds [Member]
|
||
| Fair Value | ||
| Investments at fair value | 8,754 | 9,059 |
|
Fair Value Measurements Recurring [Member] | Estimate Of Fair Value Fair Value Disclosure [Member] | U S Treasury Securities [Member]
|
||
| Fair Value | ||
| Investments at fair value | 2,029 | 2,085 |
|
Fair Value Measurements Recurring [Member] | Estimate Of Fair Value Fair Value Disclosure [Member] | U S Government Sponsored Enterprises Debt Securities [Member]
|
||
| Fair Value | ||
| Investments at fair value | 52,093 | 67,178 |
|
Fair Value Measurements Recurring [Member] | Estimate Of Fair Value Fair Value Disclosure [Member] | Corporate Bond Securities And Commercial Paper [Member]
|
||
| Fair Value | ||
| Investments at fair value | $ 94,036 | $ 133,458 |