XML 86 R66.htm IDEA: XBRL DOCUMENT v3.20.4
INVESTMENTS - Maturity Period (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Investments    
Amortized Cost $ 925,559 $ 545,771
Fair Value 925,645 545,968
Commercial paper | Less than 1 year    
Investments    
Amortized Cost 119,886 83,478
Fair Value 119,886 83,478
Municipal securities | Less than 1 year    
Investments    
Amortized Cost 9,083 147,983
Fair Value 9,083 148,108
Municipal securities | Due 1 - 10 years    
Investments    
Amortized Cost   1,562
Fair Value   1,561
U.S. government agency securities | Less than 1 year    
Investments    
Amortized Cost 81,521 40,620
Fair Value 81,531 40,590
U.S. government agency securities | Due 1 - 10 years    
Investments    
Amortized Cost 10,350 5,267
Fair Value 10,351 5,266
Certificates of deposit | Less than 1 year    
Investments    
Amortized Cost 20,387 28,049
Fair Value 20,387 28,049
U.S. treasuries | Less than 1 year    
Investments    
Amortized Cost 650,386 211,055
Fair Value 650,467 211,158
U.S. treasuries | Due 1 - 10 years    
Investments    
Amortized Cost 33,946 6,077
Fair Value $ 33,940 6,078
Variable rate demand notes | Due 1 - 10 years    
Investments    
Amortized Cost   3,905
Fair Value   3,905
Variable rate demand notes | Due 11 - 20 years    
Investments    
Amortized Cost   8,886
Fair Value   8,886
Variable rate demand notes | Due 21 - 30 years    
Investments    
Amortized Cost   6,885
Fair Value   6,885
Variable rate demand notes | Due 31 - 40 years    
Investments    
Amortized Cost   2,004
Fair Value   $ 2,004