XML 45 R31.htm IDEA: XBRL DOCUMENT v3.20.4
Note 4 - Fair Value Measurements (Tables)
12 Months Ended
Dec. 31, 2020
Notes Tables  
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]
  

December 31, 2020

 
  

Total

  

Level 1

  

Level 2

  

Level 3

 

Money market funds

 $34,335  $34,335  $-  $- 

Corporate debt securities

  249,671   -   249,671   - 

Commercial paper

  2,999   -   2,999   - 

U.S. treasuries and government agency bonds

  7,499   -   7,499   - 

Auction-rate securities backed by student-loan notes

  2,861   -   -   2,861 

Mutual funds and money market funds under deferred compensation plan

  26,924   26,924   -   - 

Total

 $324,289  $61,259  $260,169  $2,861 
  

December 31, 2019

 
  

Total

  

Level 1

  

Level 2

  

Level 3

 

Money market funds

 $28,100  $28,100  $-  $- 

Corporate debt securities

  260,950   -   260,950   - 

Commercial paper

  1,994   -   1,994   - 

U.S. treasuries and government agency bonds

  19,493   -   19,493   - 

Auction-rate securities backed by student-loan notes

  3,138   -   -   3,138 

Mutual funds and money market funds under deferred compensation plan

  21,975   21,975   -   - 

Total

 $335,650  $50,075  $282,437  $3,138 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

Balance at January 1, 2019

 $3,241 

Change in unrealized gain included in other comprehensive income

  147 

Sale and settlement at par

  (250)

Balance at December 31, 2019

  3,138 

Change in unrealized gain included in other comprehensive income

  23 

Sale and settlement at par

  (300)

Balance at December 31, 2020

 $2,861 
Fair Value Measurement Inputs and Valuation Techniques [Table Text Block]
 

December 31,

 
 

2020 (1)

  

2019

 

Time-to-liquidity (in years)

2

-3(2.5)  

2

-3 

Discount rate

3.5%

-7.9%(5.6%)  

4.0%

-8.3%