XML 76 R58.htm IDEA: XBRL DOCUMENT v3.8.0.1
Cash, Cash Equivalents and Investments - Components of Cash, Cash Equivalents and Investments (Detail) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]        
Cash $ 97,951 $ 77,307    
Money market instruments 8,631 2,334    
Cash and cash equivalents 106,582 79,641 $ 51,975 $ 55,694
Short-term investments 297,961 341,194    
Long-term investments 423,441 324,335    
Total 827,984 745,170    
Treasury Bills [Member]        
Schedule of Available-for-sale Securities [Line Items]        
Short-term investments 150,371 67,175    
Long-term investments 23,459 92,280    
Asset-Backed Securities [Member]        
Schedule of Available-for-sale Securities [Line Items]        
Short-term investments 59,203 69,614    
Long-term investments 71,727 26,946    
Corporate Bonds [Member]        
Schedule of Available-for-sale Securities [Line Items]        
Short-term investments 47,395 141,188    
Long-term investments 296,014 169,952    
Euro liquidity fund [Member]        
Schedule of Available-for-sale Securities [Line Items]        
Short-term investments 0 46,499    
Sovereign Bonds [Member]        
Schedule of Available-for-sale Securities [Line Items]        
Short-term investments 21,579 7,298    
Long-term investments 13,147 23,585    
Agency Bonds [Member]        
Schedule of Available-for-sale Securities [Line Items]        
Short-term investments 10,608 2,903    
Long-term investments 14,890 10,339    
Municipal Bonds [Member]        
Schedule of Available-for-sale Securities [Line Items]        
Short-term investments 8,805 6,517    
Long-term investments $ 4,204 $ 1,233