XML 61 R37.htm IDEA: XBRL DOCUMENT v3.8.0.1
Marketable Securities (Tables)
12 Months Ended
Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]  
Summary of Marketable Securities
Below is a summary of our marketable securities as of December 31, 2017 (in thousands):
 
 
December 31, 2017
 
 
Cost or Amortized Cost
 
Unrealized Gain, Net
 
Estimated Fair Value
Marketable securities
 
$
276,567

 
$
361

 
$
276,928