Financial Instruments (Details 1) (USD $)
In Thousands, unless otherwise specified |
Jun. 30, 2012
|
Dec. 31, 2011
|
---|---|---|
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | $ 72,161 | $ 72,082 |
Money market funds [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | 378 | 14,372 |
Fair Value Measurements Recurring [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | 72,161 | 72,082 |
Fair Value Measurements Recurring [Member] | Government debt securities [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | 12,000 | 15,969 |
Fair Value Measurements Recurring [Member] | Corporate debt securities [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | 59,783 | 41,741 |
Fair Value Measurements Recurring [Member] | Money market funds [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | 378 | 14,372 |
Fair Value Measurements Recurring [Member] | Quoted prices In Active Market For Identical Assets (Level 1) [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | 378 | 14,372 |
Fair Value Measurements Recurring [Member] | Quoted prices In Active Market For Identical Assets (Level 1) [Member] | Government debt securities [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | ||
Fair Value Measurements Recurring [Member] | Quoted prices In Active Market For Identical Assets (Level 1) [Member] | Corporate debt securities [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | ||
Fair Value Measurements Recurring [Member] | Quoted prices In Active Market For Identical Assets (Level 1) [Member] | Money market funds [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | 378 | 14,372 |
Fair Value Measurements Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | 71,783 | 57,710 |
Fair Value Measurements Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Government debt securities [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | 12,000 | 15,969 |
Fair Value Measurements Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate debt securities [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | 59,783 | 41,741 |
Fair Value Measurements Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Money market funds [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | ||
Fair Value Measurements Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | ||
Fair Value Measurements Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Government debt securities [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | ||
Fair Value Measurements Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate debt securities [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities | ||
Fair Value Measurements Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Money market funds [Member]
|
||
Financial instruments measured on recurring basis | ||
Fair value, available-for-sale securities |