Quarterly report pursuant to Section 13 or 15(d)

Fair Value (Details)

v3.5.0.2
Fair Value (Details) - USD ($)
$ in Thousands
Sep. 30, 2016
Dec. 31, 2015
Fair Value    
Investments at fair value $ 70,359 $ 97,867
Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value 81,541 124,158
U.S. treasury securities    
Fair Value    
Investments at fair value 8,307 9,048
U.S. Government-sponsored enterprises securities    
Fair Value    
Investments at fair value 16,825 48,613
Corporate bonds and commercial paper    
Fair Value    
Investments at fair value 45,227 40,206
Fair value inputs Level 1    
Fair Value    
Investments at fair value 11,182 26,291
Fair value inputs Level 2    
Fair Value    
Investments at fair value 70,359 97,867
Fair value measurements recurring | Money market funds | Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value 11,182 26,291
Fair value measurements recurring | U.S. treasury securities | Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value 8,307 9,048
Fair value measurements recurring | U.S. Government-sponsored enterprises securities | Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value 16,825 48,613
Fair value measurements recurring | Corporate bonds and commercial paper | Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value 45,227 40,206
Fair value measurements recurring | Fair value inputs Level 1 | Money market funds    
Fair Value    
Investments at fair value 11,182 26,291
Fair value measurements recurring | Fair value inputs Level 2 | U.S. treasury securities    
Fair Value    
Investments at fair value 8,307 9,048
Fair value measurements recurring | Fair value inputs Level 2 | U.S. Government-sponsored enterprises securities    
Fair Value    
Investments at fair value 16,825 48,613
Fair value measurements recurring | Fair value inputs Level 2 | Corporate bonds and commercial paper    
Fair Value    
Investments at fair value $ 45,227 $ 40,206