XML 42 R30.htm IDEA: XBRL DOCUMENT v3.8.0.1
Short-term Investments - Available-For-Sale Securities Reported At Fair Value (Details) - USD ($)
$ in Thousands
Sep. 30, 2017
Dec. 31, 2016
Level 1 Securities | Money market funds    
Schedule of Available-for-sale Securities [Line Items]    
Cash and Money Market Funds, Estimated Fair Value   $ 204,967
Level 2 Securities | Certificates of deposit    
Schedule of Available-for-sale Securities [Line Items]    
Level 2 securities, Estimated Fair Value   9,833
Cash    
Schedule of Available-for-sale Securities [Line Items]    
Cash and Money Market Funds, Estimated Fair Value   1,267,523
Fair Value, Measurements, Recurring    
Schedule of Available-for-sale Securities [Line Items]    
Level 2 securities, Gross Unrealized Gains   110
Level 2 securities, Gross Unrealized Losses   (1,087)
Total, amortized cost   1,739,673
Total, estimated fair value   1,738,696
Fair Value, Measurements, Recurring | Level 1 Securities | Money market funds    
Schedule of Available-for-sale Securities [Line Items]    
Cash and Money Market Funds, Amortized Cost   204,967
Cash and Money Market Funds, Estimated Fair Value   203,450
Cash, Cash Equivalents and Restricted Cash, Noncurrent Assets   1,517
Fair Value, Measurements, Recurring | Level 2 Securities | Corporate debt securities    
Schedule of Available-for-sale Securities [Line Items]    
Level 2 securities, Amortized Cost   199,843
Level 2 securities, Gross Unrealized Gains   110
Level 2 securities, Gross Unrealized Losses   (731)
Level 2 securities, Estimated Fair Value   199,222
Fair Value, Measurements, Recurring | Level 2 Securities | Government securities    
Schedule of Available-for-sale Securities [Line Items]    
Level 2 securities, Amortized Cost   35,944
Level 2 securities, Gross Unrealized Losses   (128)
Level 2 securities, Estimated Fair Value   35,816
Fair Value, Measurements, Recurring | Level 2 Securities | Certificates of deposit    
Schedule of Available-for-sale Securities [Line Items]    
Level 2 securities, Amortized Cost   9,833
Level 2 securities, Estimated Fair Value   9,833
Fair Value, Measurements, Recurring | Level 2 Securities | Agency securities    
Schedule of Available-for-sale Securities [Line Items]    
Level 2 securities, Amortized Cost   21,563
Level 2 securities, Gross Unrealized Losses   (228)
Level 2 securities, Estimated Fair Value   21,335
Fair Value, Measurements, Recurring | Cash    
Schedule of Available-for-sale Securities [Line Items]    
Cash and Money Market Funds, Amortized Cost   1,267,523
Cash and Money Market Funds, Estimated Fair Value   1,264,126
Cash, Cash Equivalents and Restricted Cash, Noncurrent Assets $ 3,600 3,397
Cash and Cash Equivalents | Fair Value, Measurements, Recurring    
Schedule of Available-for-sale Securities [Line Items]    
Total, estimated fair value   1,467,576
Cash and Cash Equivalents | Fair Value, Measurements, Recurring | Level 1 Securities | Money market funds    
Schedule of Available-for-sale Securities [Line Items]    
Cash and Money Market Funds, Amortized Cost 13,900  
Short-term Investments | Fair Value, Measurements, Recurring    
Schedule of Available-for-sale Securities [Line Items]    
Total, estimated fair value   266,206
Non-current Assets | Fair Value, Measurements, Recurring    
Schedule of Available-for-sale Securities [Line Items]    
Total, estimated fair value   $ 4,914
Non-current Assets | Fair Value, Measurements, Recurring | Level 1 Securities | Money market funds    
Schedule of Available-for-sale Securities [Line Items]    
Cash and Money Market Funds, Amortized Cost $ 1,300