v3.25.2
Debt - Schedule of Selected Information about Debt Issues (Details) - USD ($)
 6 Months Ended
Jun. 30, 2025
Dec. 31, 2024
Jun. 30, 2024
Debt Instrument [Line Items]      
Long-term debt, par value, gross $ 2,350,000,000    
Total short-term debt, par value 467,000,000    
Total debt, par value 2,817,000,000    
Unamortized discount & issuance costs, noncurrent (24,358,000)    
Unamortized discount & issuance costs, current (2,460,000)    
Total debt, unamortized discount & issuance costs, (26,818,000)    
Long-term debt 2,325,642,000 $ 2,324,251,000  
Total short-term debt, book value 464,540,000 415,401,000  
Total debt, book value 2,790,182,000 2,739,652,000  
Fair Value 2,172,267,000    
Total short-term debt, fair value 464,540,000    
Total debt, fair value 2,636,807,000    
FHLB borrowings      
Debt Instrument [Line Items]      
Total short-term debt, par value 70,000,000   $ 180,000,000
Unamortized discount & issuance costs, current 0    
Total short-term debt, book value 70,000,000 0  
Total short-term debt, fair value 70,000,000    
Commercial paper      
Debt Instrument [Line Items]      
Total short-term debt, par value 397,000,000    
Unamortized discount & issuance costs, current (2,460,000)    
Total short-term debt, book value 394,540,000 415,401,000  
Total short-term debt, fair value $ 394,540,000    
Senior Notes Due 2028      
Debt Instrument [Line Items]      
Coupon Rate 4.55%    
Long-term debt, par value, gross $ 550,000,000    
Unamortized discount & issuance costs, noncurrent (2,627,000)    
Debt 547,373,000 546,999,000  
Long-term debt, gross, fair value $ 552,519,000    
Senior Notes Due 2030      
Debt Instrument [Line Items]      
Coupon Rate 2.15%    
Long-term debt, par value, gross $ 400,000,000    
Unamortized discount & issuance costs, noncurrent (2,632,000)    
Debt 397,368,000 397,132,000  
Long-term debt, gross, fair value $ 353,416,000    
Senior Notes Due 2032      
Debt Instrument [Line Items]      
Coupon Rate 4.80%    
Long-term debt, par value, gross $ 250,000,000    
Unamortized discount & issuance costs, noncurrent (3,518,000)    
Debt 246,482,000 246,272,000  
Long-term debt, gross, fair value 245,922,000    
Senior Notes Due 2032 | Consolidation Eliminations | Subsidiaries      
Debt Instrument [Line Items]      
Long-term debt, net, book value $ 150,000,000    
Senior Notes Due 2034      
Debt Instrument [Line Items]      
Coupon Rate 5.85%    
Long-term debt, par value, gross $ 450,000,000    
Unamortized discount & issuance costs, noncurrent (4,984,000)    
Debt 445,016,000 444,814,000  
Long-term debt, gross, fair value $ 465,089,000    
Junior Subordinated Debentures Due 2057      
Debt Instrument [Line Items]      
Coupon Rate 5.275%    
Long-term debt, par value, gross $ 125,000,000    
Unamortized discount & issuance costs, noncurrent (1,548,000)    
Debt 123,452,000 123,443,000  
Long-term debt, gross, fair value $ 97,500,000    
Basis spread 1.35%    
Junior Subordinated Debentures Due 2061      
Debt Instrument [Line Items]      
Coupon Rate 4.25%    
Long-term debt, par value, gross $ 325,000,000    
Unamortized discount & issuance costs, noncurrent (7,570,000)    
Debt 317,430,000 317,387,000  
Long-term debt, gross, fair value $ 209,300,000    
Term Loan Due 2027      
Debt Instrument [Line Items]      
Coupon Rate 5.799%    
Long-term debt, par value, gross $ 250,000,000    
Unamortized discount & issuance costs, noncurrent (1,479,000)    
Debt 248,521,000 $ 248,204,000  
Long-term debt, gross, fair value $ 248,521,000