Quarterly report pursuant to Section 13 or 15(d)

Fair Value (Details)

v3.2.0.727
Fair Value (Details) - USD ($)
$ in Thousands
Jun. 30, 2015
Dec. 31, 2014
Fair Value    
Investments at fair value $ 128,156 $ 132,957
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 46,378 45,786
Corporate Bond Securities And Commercial Paper    
Fair Value    
Investments at fair value 81,778 85,161
Fair Value Inputs Level1    
Fair Value    
Investments at fair value 15,593 10,027
Fair Value Inputs Level2    
Fair Value    
Investments at fair value 128,156 132,957
Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value 143,749 142,984
Fair Value Measurements Recurring | Money Market Funds    
Fair Value    
Investments at fair value 15,593 10,027
Fair Value Measurements Recurring | U S Treasury Securities    
Fair Value    
Investments at fair value   2,010
Fair Value Measurements Recurring | U S Government Sponsored Enterprises Debt Securities    
Fair Value    
Investments at fair value 46,378 45,786
Fair Value Measurements Recurring | Corporate Bond Securities And Commercial Paper    
Fair Value    
Investments at fair value 81,778 85,161
Fair Value Measurements Recurring | Fair Value Inputs Level1 | Money Market Funds    
Fair Value    
Investments at fair value 15,593 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 46,378 45,786
Fair Value Measurements Recurring | Fair Value Inputs Level2 | Corporate Bond Securities And Commercial Paper    
Fair Value    
Investments at fair value $ 81,778 $ 85,161