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Significant Accounting Policies (Details Textual) (USD $)
In Thousands, except Share data in Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Summary of Significant Accounting Policies (Textual) [Abstract]    
Original Maturities of Highly Liquid Financial Instruments Three months or less  
Contractual maturity of a particular investment 1 year  
Number of financial institutions 1  
Impairment charges on marketable securities other-than-temporary declines 0  
Respective stock option 4 years  
Stock Options [Member]
   
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Weighted options outstanding to purchase common stock 14.4 12.1