XML 93 R84.htm IDEA: XBRL DOCUMENT v3.20.2
Fair Value Measurement (Details) - USD ($)
$ in Thousands
Dec. 31, 2019
Dec. 31, 2018
Schedule of assets and liabilities measured at fair value on a recurring basis    
Money market funds $ 419,693 $ 311,732
Marketable securities 71,507 74,799
Liabilities:    
Accounts payable and accrued liabilities 90,828 85,979
Recurring    
Schedule of assets and liabilities measured at fair value on a recurring basis    
Total assets at fair value on a recurring basis 102,200 77,090
Money market funds | Recurring    
Schedule of assets and liabilities measured at fair value on a recurring basis    
Money market funds 30,693 1,791
Corporate debt securities    
Schedule of assets and liabilities measured at fair value on a recurring basis    
Marketable securities 42,709 47,930
Corporate debt securities | Recurring    
Schedule of assets and liabilities measured at fair value on a recurring basis    
Marketable securities 42,709 48,430
Tax-exempt municipal securities    
Schedule of assets and liabilities measured at fair value on a recurring basis    
Marketable securities 23,198 22,869
Tax-exempt municipal securities | Recurring    
Schedule of assets and liabilities measured at fair value on a recurring basis    
Marketable securities 23,198 22,869
Variable rate demand notes    
Schedule of assets and liabilities measured at fair value on a recurring basis    
Marketable securities 5,600 4,000
Variable rate demand notes | Recurring    
Schedule of assets and liabilities measured at fair value on a recurring basis    
Marketable securities 5,600 4,000
Deferred payments | Recurring    
Liabilities:    
Accounts payable and accrued liabilities 3,257 4,120
Quoted Prices In Active Markets For Identical Assets/Liabilities (Level 1) | Recurring    
Schedule of assets and liabilities measured at fair value on a recurring basis    
Total assets at fair value on a recurring basis 30,693 1,791
Quoted Prices In Active Markets For Identical Assets/Liabilities (Level 1) | Money market funds | Recurring    
Schedule of assets and liabilities measured at fair value on a recurring basis    
Money market funds 30,693 1,791
Significant Other Observable Inputs (Level 2) | Recurring    
Schedule of assets and liabilities measured at fair value on a recurring basis    
Total assets at fair value on a recurring basis 71,507 75,299
Significant Other Observable Inputs (Level 2) | Corporate debt securities | Recurring    
Schedule of assets and liabilities measured at fair value on a recurring basis    
Marketable securities 42,709 48,430
Significant Other Observable Inputs (Level 2) | Tax-exempt municipal securities | Recurring    
Schedule of assets and liabilities measured at fair value on a recurring basis    
Marketable securities 23,198 22,869
Significant Other Observable Inputs (Level 2) | Variable rate demand notes | Recurring    
Schedule of assets and liabilities measured at fair value on a recurring basis    
Marketable securities 5,600 4,000
Significant Unobservable Inputs (Level 3) | Deferred payments | Recurring    
Liabilities:    
Accounts payable and accrued liabilities $ 3,257 $ 4,120