Fair Value Measurements (Tables)
3 Months Ended
Mar. 31, 2015
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:
 
 
March 31, 2015
Description
 
Level 1
 
Level 2
 
Level 3
 
Total
 
 
(in thousands)
Money market funds
 
$
689,475

 
$

 
$

 
$
689,475

 
 
 
 
 
 
 
 
 
 
 
December 31, 2014
Description
 
Level 1
 
Level 2
 
Level 3
 
Total
 
 
(in thousands)
Money market funds
 
$
667,210

 
$

 
$

 
$
667,210