|
Summary of Significant Accounting Policies (Details 5) (Fair Value, Measurements, Recurring [Member], USD $)
In Thousands, unless otherwise specified |
Dec. 31, 2011
|
Jan. 01, 2011
|
|---|---|---|
|
Level 1 [Member]
|
||
| Asset | ||
| Total assets measured at fair value | $ 117,196 | $ 5,090 |
|
Level 1 [Member] | Money Market Funds [Member]
|
||
| Asset | ||
| Total assets measured at fair value | 117,196 | 5,090 |
|
Level 1 [Member] | U.S. Government bond [Member]
|
||
| Asset | ||
| Total assets measured at fair value | 0 | 0 |
|
Level 1 [Member] | Corporate bond [Member]
|
||
| Asset | ||
| Total assets measured at fair value | 0 | 0 |
|
Level 2 [Member]
|
||
| Asset | ||
| Total assets measured at fair value | 17,811 | 13,928 |
|
Level 2 [Member] | Money Market Funds [Member]
|
||
| Asset | ||
| Total assets measured at fair value | 0 | 0 |
|
Level 2 [Member] | U.S. Government bond [Member]
|
||
| Asset | ||
| Total assets measured at fair value | 2,502 | 2,504 |
|
Level 2 [Member] | Corporate bond [Member]
|
||
| Asset | ||
| Total assets measured at fair value | 15,309 | 11,424 |
|
Level 3 [Member]
|
||
| Asset | ||
| Total assets measured at fair value | 0 | 0 |
|
Level 3 [Member] | Money Market Funds [Member]
|
||
| Asset | ||
| Total assets measured at fair value | 0 | 0 |
|
Level 3 [Member] | U.S. Government bond [Member]
|
||
| Asset | ||
| Total assets measured at fair value | 0 | 0 |
|
Level 3 [Member] | Corporate bond [Member]
|
||
| Asset | ||
| Total assets measured at fair value | $ 0 | $ 0 |