Employee Benefit Plan (Details)	12 Months Ended
Dec. 31, 2012
Employee Benefit Plan
Maximum percentage of compensation that the employees may contribute to the 401 (k) plan	60.00%
Employer matching contribution (as a percent)	50.00%
Employer's matching contribution as a percentage of employee's compensation, maximum	3.00%

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration