|
Employee Benefit Plan (Details) (USD $)
|
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2011
|
Dec. 31, 2010
|
Dec. 31, 2009
|
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| Employee Benefit Plan | |||
| Employee contribution limit per calendar year | $ 16,500 | ||
| Employer contribution as a percentage of the employee contribution up to 6% of gross earnings | 25.00% | ||
| Employer contribution limit per calendar year (as a percent of gross earnings) | 6.00% | ||
| Matching contributions | $ 570,000 | $ 358,000 | $ 159,000 |