v3.26.1
Note 8 - Equity Compensation Plans (Tables)
6 Months Ended
Jun. 30, 2026
Notes Tables  
Share-Based Payment Arrangement, Option, Activity [Table Text Block]
  

Stock Option

  

Restricted Stock

  

PSU

 
  

Number of Options

  

Weighted Average Exercise Price

  

Aggregate Intrinsic Value

  

Number of Shares

  

Weighted Average Grant Date Fair Value Per Share

  

Number of Shares

   

Weighted Average Grant Date Fair Value Per Share

 
                              

Outstanding at December 31, 2025

  1,676,340  $180.40  $72.6   321,947  $242.66   135,916   $262.39 

Granted

  293,498  $220.59       192,701  $219.78   102,583   $224.35 

Dividend reinvestment

                  830    N/A 

Exercised or lapsed

  (127,648) $122.90  $9.0   (122,754) $227.55   (45,252)  $204.30 

Canceled, expired or forfeited

  (41,669) $220.88       (14,713) $239.39   (1,697)  $285.56 

Outstanding at June 30, 2026

  1,800,521  $190.09  $28.0   377,181  $234.32   192,380   $264.39 

Exercisable at June 30, 2026

  1,232,127  $170.16  $27.9                  

Exercisable at December 31, 2025

  1,178,052  $156.76  $78.8                  

Nonvested at June 30, 2026

  568,394           377,181       192,380      

Expected to vest at June 30, 2026

  487,811           335,537       76,002 

(1)

    
Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]
  

2026

  

2025

 

Option pricing model

 

Black-Scholes

  

Black-Scholes

 

Weighted average grant price

 

$220.59

  

$273.92

 

Expected volatility

 

22.94

% 

22.00

%

Risk-free interest rate

 

3.68

% 

4.37

%

Expected term in years

 

3.7

  

3.5

 

Dividend yield

 

0.65

% 

0.62

%

Weighted average grant date fair value per stock option

 

$48.15

  

$59.50