Note 7 - Equity Incentive Plans	9 Months Ended
Sep. 30, 2021
Notes to Financial Statements
Share-based Payment Arrangement [Text Block]	Note 7 – Equity Incentive Plans: Total compensation cost for share-based payments recognized for the three and nine months ended September 30, 2021 was $5,746 and $18,587, respectively and for the three and nine months ended September 30, 2020 was $3,410 and $7,984, respectively. During the nine months ended September 30, 2021, 85 and 118 service period stock options and performance stock options, respectively, were exercised. During the nine months ended September 30, 2021, 32 service period restricted stock units were granted at a weighted average grant-date fair market value of $155.67. During the nine months ended September 30, 2021, 74 service period restricted stock units vested.

Note 7 - Equity Incentive Plans

9 Months Ended

Sep. 30, 2021

Share-based Payment Arrangement [Text Block]

Note 7 – Equity Incentive Plans:

Total compensation cost for share-based payments recognized for the three and nine months ended September 30, 2021 was $5,746 and $18,587, respectively and for the three and nine months ended September 30, 2020 was $3,410 and $7,984, respectively. During the nine months ended September 30, 2021, 85 and 118 service period stock options and performance stock options, respectively, were exercised. During the nine months ended September 30, 2021, 32 service period restricted stock units were granted at a weighted average grant-date fair market value of $155.67. During the nine months ended September 30, 2021, 74 service period restricted stock units vested.