Quarterly report pursuant to Section 13 or 15(d)

Consolidated Statements of Stockholders' Equity (Parenthetical)

v3.23.4
Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Nov. 30, 2023
Nov. 30, 2022
Nov. 30, 2023
Nov. 30, 2022
Unrealized gains (losses) on securities, tax $ 4.8 $ (10.3) $ (2.8) $ (20.0)
Reclassification adjustment for realized gains (loss) on securities, tax $ (0.0) $ 0.0 $ (0.0) $ 0.0
Cash dividends declared, per share $ 0.89 $ 0.79 $ 1.78 $ 1.58
Authorized In January 2024 [Member]        
Expiration date     Jan. 31, 2024  
Authorized In January 2024 [Member] | Maximum [Member]        
Approved repurchase amount $ 400.0   $ 400.0