XML 66 R47.htm IDEA: XBRL DOCUMENT v3.20.4
Marketable Securities - Available-For-Sale Marketable Securities (Detail) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost $ 306,504 $ 266,750
Gross Unrealized Gains 216 313
Gross Unrealized Losses (11) (6)
Fair Market Value 306,709 267,057
U.S. Treasury and government agencies    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 165,966 88,535
Gross Unrealized Gains 129 68
Gross Unrealized Losses (3) (2)
Fair Market Value 166,092 88,601
Corporate debt    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 140,538 129,860
Gross Unrealized Gains 87 196
Gross Unrealized Losses (8) (1)
Fair Market Value $ 140,617 130,055
Asset-backed securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost   48,355
Gross Unrealized Gains   49
Gross Unrealized Losses   (3)
Fair Market Value   $ 48,401