XML 63 R52.htm IDEA: XBRL DOCUMENT v3.25.1
Investments - Ratings and Fair Value of Debt Securities (Details) - USD ($)
$ in Millions
Mar. 31, 2025
Dec. 31, 2024
Debt and Equity Securities, FV-NI [Line Items]    
Debt securities, available-for-sale $ 4,635.2 $ 5,131.0
Debt securities, trading 117.6 162.2
AAA    
Debt and Equity Securities, FV-NI [Line Items]    
Debt securities, available-for-sale 703.0 808.5
Debt securities, trading 41.5 74.0
AA    
Debt and Equity Securities, FV-NI [Line Items]    
Debt securities, available-for-sale 2,111.7 2,227.9
Debt securities, trading 33.5 54.0
A    
Debt and Equity Securities, FV-NI [Line Items]    
Debt securities, available-for-sale 1,039.1 1,375.0
Debt securities, trading 15.4 6.9
BBB    
Debt and Equity Securities, FV-NI [Line Items]    
Debt securities, available-for-sale 638.9 659.2
Debt securities, trading 24.7 24.2
Other    
Debt and Equity Securities, FV-NI [Line Items]    
Debt securities, available-for-sale 142.5 60.4
Debt securities, trading $ 2.5 $ 3.1