Employee 401(k) Plan (Details) (USD $)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Employee 401(k) Plan
Maximum percentage of pretax salary, which can be deferred by employees	20.00%
Maximum amount of wages, which can be deferred by employees	$ 17,000
Maximum amount of wages, which can be deferred by employees at least 50 years of age	22,500
Minimum age of employees for a specified contribution amount of wages	50 years
Percentage of employee's salary for which the company contributes a matching contribution	50.00%
Maximum percentage of employee's salary for which the company contributes a matching contribution	8.00%
Amount of employer contribution	$ 334,122	$ 306,837	$ 303,000

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The amount of the cost recognized during the period for defined contribution plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 70

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 11

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Maximum percentage of employee gross pay, by the terms of the plan, that the employer may contribute to a defined contribution plan.

+ References

No definition available.

+ Details

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- Definition

Represents the maximum amount of wages, which can be deferred by participants of the defined contribution plans.

+ References

No definition available.

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- Definition

Represents the maximum amount of wages, which can be deferred by participants with a specified age, for defined contribution plans.

+ References

No definition available.

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- Definition

Represents the maximum percentage of pretax salary, which can be deferred by participants of the defined contribution plans.

+ References

No definition available.

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- Definition

Represents the maximum amount of wages, which can be deferred by participants with a specified age, for defined contribution plans.

+ References

No definition available.

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