Available-for-sale Securities (Details 1) (USD $)
In Thousands, unless otherwise specified
Sep. 30, 2012
Dec. 31, 2011
Classification of the available-for-sale securities    
Available for sale securities total $ 98,397 $ 61,141
Cash and cash equivalents [Member]
   
Classification of the available-for-sale securities    
Available for sale securities total 69,563 9,238
Marketable securities [Member]
   
Classification of the available-for-sale securities    
Available for sale securities total 28,634 51,703
Restricted cash [Member]
   
Classification of the available-for-sale securities    
Available for sale securities total $ 200 $ 200