Quarterly report pursuant to Section 13 or 15(d)

Fair Value (Details)

v3.3.0.814
Fair Value (Details) - USD ($)
$ in Thousands
Sep. 30, 2015
Dec. 31, 2014
Fair Value    
Investments at fair value $ 108,222 $ 132,957
Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value 132,327 142,984
U S Treasury Securities    
Fair Value    
Investments at fair value   2,010
U S Government Sponsored Enterprises Debt Securities    
Fair Value    
Investments at fair value 50,260 45,786
Corporate Bond Securities And Commercial Paper    
Fair Value    
Investments at fair value 57,962 85,161
Fair Value Inputs Level1    
Fair Value    
Investments at fair value 24,105 10,027
Fair Value Inputs Level2    
Fair Value    
Investments at fair value 108,222 132,957
Fair Value Measurements Recurring | Money Market Funds | Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value 24,105 10,027
Fair Value Measurements Recurring | U S Treasury Securities | Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value   2,010
Fair Value Measurements Recurring | U S Government Sponsored Enterprises Debt Securities | Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value 50,260 45,786
Fair Value Measurements Recurring | Corporate Bond Securities And Commercial Paper | Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value 57,962 85,161
Fair Value Measurements Recurring | Fair Value Inputs Level1 | Money Market Funds    
Fair Value    
Investments at fair value 24,105 10,027
Fair Value Measurements Recurring | Fair Value Inputs Level2 | U S Treasury Securities    
Fair Value    
Investments at fair value   2,010
Fair Value Measurements Recurring | Fair Value Inputs Level2 | U S Government Sponsored Enterprises Debt Securities    
Fair Value    
Investments at fair value 50,260 45,786
Fair Value Measurements Recurring | Fair Value Inputs Level2 | Corporate Bond Securities And Commercial Paper    
Fair Value    
Investments at fair value $ 57,962 $ 85,161