XML 82 R60.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
INVESTMENTS - Schedule of cash, cash equivalents and short-term investments (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]      
Cash and cash equivalents, Amortized Cost $ 77,579 $ 56,766 $ 62,473
Cash and cash equivalents, Estimated Fair Value 77,579 56,766  
Short-term Investments, Amortized Cost 796,710 382,100  
Short-term Investments, Estimated Fair Value 798,318 381,724  
Cash, cash equivalents and short-term investments, Amortized Cost 874,289 438,866  
Cash, cash equivalents and short-term investments, Estimated Fair Value 875,897 438,490  
Gains/losses on short-term investments 15,600 5,600  
Unrealized gains 1,900 100  
Unrealized losses 300 500  
Cash and cash equivalents      
Debt Securities, Available-for-sale [Line Items]      
Cash and cash equivalents, Amortized Cost 76,521 55,501  
Cash and cash equivalents, Estimated Fair Value 76,521 55,501  
Money market funds      
Debt Securities, Available-for-sale [Line Items]      
Cash and cash equivalents, Amortized Cost 1,058 1,265  
Cash and cash equivalents, Estimated Fair Value 1,058 1,265  
Certificates of deposit      
Debt Securities, Available-for-sale [Line Items]      
Short-term Investments, Amortized Cost 198,561 95,080  
Short-term Investments, Estimated Fair Value 198,663 95,038  
Government debt securities      
Debt Securities, Available-for-sale [Line Items]      
Short-term Investments, Amortized Cost 232,357 100,449  
Short-term Investments, Estimated Fair Value 232,604 100,478  
Corporate debt securities      
Debt Securities, Available-for-sale [Line Items]      
Short-term Investments, Amortized Cost 365,792 186,571  
Short-term Investments, Estimated Fair Value $ 367,051 $ 186,208