Fair Value Measurements (Tables)
 6 Months Ended
Jun. 30, 2017
Fair Value Disclosures [Abstract]  
Fair Value of Financial Assets
The following table presents the fair value of our financial assets using the fair value hierarchy:
 
 
June 30, 2017
Description
 
Level 1
 
Level 2
 
Level 3
 
Total
 
 
(in thousands)
Money market funds
 
$
952,661

 
$
—

 
$
—

 
$
952,661

 
 
 
 
 
 
 
 
 
 
 
December 31, 2016
Description
 
Level 1
 
Level 2
 
Level 3
 
Total
 
 
(in thousands)
Money market funds
 
$
872,161

 
$
—

 
$
—

 
$
872,161