v3.24.3
Note 12 - Compensation Plans - Summary of Stock Activity (Details) - USD ($)
$ / shares in Units, $ in Millions
 6 Months Ended 9 Months Ended
Jun. 30, 2024
Sep. 30, 2024
Sep. 30, 2023
Dec. 31, 2023
Outstanding beginning balance, options (in shares) 2,712,510 2,712,510    
Outstanding beginning balance, options, weighted average exercise price (in dollars per share) $ 143.91 $ 143.91    
Outstanding, options, aggregate intrinsic value   $ 217.7   $ 257.6
Granted, options (in shares)   203,884    
Weighted average grant price (in dollars per share)   $ 237.1 $ 185.01  
Dividend reinvestment, options (in shares)   0    
Dividend reinvestment, options, weighted average exercise price (in (in dollars per share)   $ 0    
Exercised or lapsed, options (in shares)   (873,272)    
Exercised or lapsed, options, weighted average exercise price (in dollars per share)   $ 126.5    
Exercised or lapsed, options, aggregate intrinsic value   $ 110.0    
Canceled, expired or forfeited, option (in shares) (24,530)      
Canceled, expired or forfeited, options, weighted average exercise price (in dollars per share) $ 202.41      
Outstanding, option (in shares)   2,018,592    
Outstanding beginning balance, options, weighted average exercise price (in dollars per share)   $ 160.13    
Exercisable, options (in shares)   1,428,502   1,947,253
Exercisable, options, weighted average exercise price (in dollars per share)   $ 141.31   $ 127.43
Exercisable, options, aggregate intrinsic value   $ 180.9   $ 217.0
Nonvested, options (in shares)   590,090    
Expected to vest, options (in shares)   484,269    
Restricted Stock [Member]        
Outstanding beginning balance, number of shares (in shares) 291,039 291,039    
Outstanding beginning balance, weighted average exercise price (in dollars per share) $ 186.28 $ 186.28    
Granted, number of shares (in shares)   151,242    
Granted, weighted average exercise price (in dollars per share)   $ 237.11    
Dividend reinvestment, number of shares (in shares)   0    
Dividend reinvestment (in dollars per share)   $ 0    
Exercised or lapsed, number of shares (in shares)   (104,359)    
Exercised or lapsed, weighted average exercise price (in dollars per share)   $ 187.8    
Canceled, expired or forfeited, number of shares (in shares)   (15,732)    
Canceled, expired or forfeited, weighted average exercise price (in dollars per share)   $ 206.87    
Outstanding ending balance, number of shares (in shares)   322,190    
Outstanding ending balance, weighted average exercise price (in dollars per share)   $ 208.87    
Nonvested, number of shares (in shares)   322,190   291,039
Expected, number of shares (in shares)   278,938    
Performance Shares [Member]        
Outstanding beginning balance, number of shares (in shares) 181,236 181,236    
Outstanding beginning balance, weighted average exercise price (in dollars per share) $ 199.62 $ 199.62    
Granted, number of shares (in shares)   47,838    
Granted, weighted average exercise price (in dollars per share)   $ 265.94    
Dividend reinvestment, number of shares (in shares)   825    
Exercised or lapsed, number of shares (in shares)   (47,821)    
Canceled, expired or forfeited, number of shares (in shares)   (1,870)    
Canceled, expired or forfeited, weighted average exercise price (in dollars per share)   $ 210.07    
Outstanding ending balance, number of shares (in shares)   180,208    
Outstanding ending balance, weighted average exercise price (in dollars per share)   $ 205.1    
Nonvested, number of shares (in shares)   180,208   181,236
Expected, number of shares (in shares) [1]   241,864    
[1] Includes estimated performance achievement