Quarterly report [Sections 13 or 15(d)]

Consolidated Statements of Stockholders' Equity (Parenthetical)

v3.25.1
Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Feb. 28, 2025
Feb. 29, 2024
Feb. 28, 2025
Feb. 29, 2024
Unrealized gains (losses) on securities, tax $ 4.3 $ 6.3 $ 23.2 $ 3.5
Reclassification adjustment for realized earnings (losses) on securities, tax $ 0.1 $ 0.0 $ 0.1 $ 0.0
Cash dividends declared, per share $ 0.98 $ 0.89 $ 2.94 $ 2.67
Repurchases of common shares, excise taxes $ 0.0   $ 0.5  
Authorized In July 2021 [Member]        
Expiration date     Jan. 31, 2024  
Authorized In July 2021 [Member] | Maximum [Member]        
Approved repurchase amount 400.0   $ 400.0  
Authorized In January 2024 [Member]        
Approved repurchase amount $ 400.0 $ 400.0 $ 400.0 $ 400.0
Expiration date     May 31, 2027 Jan. 31, 2024
Authorized In January 19 2024 [Member]        
Expiration date       May 31, 2027
Authorized In January 19 2024 [Member] | Maximum [Member]        
Approved repurchase amount   $ 400.0   $ 400.0