Quarterly report pursuant to Section 13 or 15(d)

Significant Accounting Policies (Investment Categories) (Details)

v3.5.0.2
Significant Accounting Policies (Investment Categories) (Details) - USD ($)
$ in Thousands
Mar. 31, 2016
Dec. 31, 2015
Summary of investment categories    
Amortized cost $ 78,923 $ 97,891
Gross unrealized gains 2,988 4,944
Gross unrealized losses (3) (44)
Estimated fair value 81,908 102,791
Bank deposits    
Summary of investment categories    
Amortized cost 42,376 43,043
Gross unrealized gains 87 0
Gross unrealized losses 0 (4)
Estimated fair value 42,463 43,039
Corporate bonds    
Summary of investment categories    
Amortized cost 24,268 41,238
Gross unrealized gains 84 0
Gross unrealized losses (2) (35)
Estimated fair value 24,350 41,203
Commercial paper    
Summary of investment categories    
Amortized cost 8,401 1,747
Gross unrealized gains 2 0
Gross unrealized losses 0 0
Estimated fair value 8,403 1,747
Asset backed securities    
Summary of investment categories    
Amortized cost 2,067 10,020
Gross unrealized gains 1 0
Gross unrealized losses (1) (5)
Estimated fair value 2,067 10,015
Corporate equity securities    
Summary of investment categories    
Amortized cost 1,811 1,843
Gross unrealized gains 2,814 4,944
Gross unrealized losses 0 0
Estimated fair value $ 4,625 $ 6,787