Note 4 - Fair Value Measurements (Tables)
|3 Months Ended|
Mar. 31, 2022
|Debt Securities, Available-for-Sale [Table Text Block]||
Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).
Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef