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Organization and Summary of Significant Accounting Policies Marketable Securities (Details) (USD $)
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Schedule of Available-for-sale Securities [Line Items]        
Trading Securities $ 0 $ 0    
Held-to-maturity Securities, Fair Value 0 0    
Cash and cash equivalents 62,313,000 191,762,000 175,635,000 169,230,000
US States and Political Subdivisions Debt Securities [Member]
       
Schedule of Available-for-sale Securities [Line Items]        
Available-for-sale Securities, Amortized Cost Basis   8,106,000    
A-F-S, Fair Value Disclosure   8,107,000    
Money Market Funds [Member]
       
Schedule of Available-for-sale Securities [Line Items]        
Cash and cash equivalents 38,892,000 177,310,000    
Cash and Cash Equivalents, Fair Value Disclosure 38,891,000 177,310,000    
Cash and Cash Equivalents [Member] | Money Market Funds [Member]
       
Schedule of Available-for-sale Securities [Line Items]        
Cash and Cash Equivalents, Fair Value Disclosure 38,891,000 177,310,000    
Short-term Investments [Member] | US States and Political Subdivisions Debt Securities [Member]
       
Schedule of Available-for-sale Securities [Line Items]        
A-F-S, Fair Value Disclosure   $ 8,107,000