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
Jun. 30, 2016
Dec. 31, 2015
Summary of investment categories    
Amortized cost $ 42,270 $ 97,891
Gross unrealized gains 3,334 4,944
Gross unrealized losses (1) (44)
Estimated fair value 45,603 102,791
Bank deposits    
Summary of investment categories    
Amortized cost 10,000 43,043
Gross unrealized gains 28 0
Gross unrealized losses 0 (4)
Estimated fair value 10,028 43,039
Corporate bonds    
Summary of investment categories    
Amortized cost 23,210 41,238
Gross unrealized gains 174 0
Gross unrealized losses (1) (35)
Estimated fair value 23,383 41,203
Commercial paper    
Summary of investment categories    
Amortized cost 6,665 1,747
Gross unrealized gains 3 0
Gross unrealized losses 0 0
Estimated fair value 6,668 1,747
Asset backed securities    
Summary of investment categories    
Amortized cost 695 10,020
Gross unrealized gains 0 0
Gross unrealized losses 0 (5)
Estimated fair value 695 10,015
Corporate equity securities    
Summary of investment categories    
Amortized cost 1,700 1,843
Gross unrealized gains 3,129 4,944
Gross unrealized losses 0 0
Estimated fair value $ 4,829 $ 6,787