v3.25.4
Reinsurance Contract Assets Held - Movements in reinsurance contract assets held (Details) - Property and Casualty Insurance and Reinsurance - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Jan. 01, 2025
Jan. 01, 2024
Reinsurance contracts assets held        
Reinsurance Contract Assets Held        
Beginning Balance $ 9,748.3 $ 9,853.7    
Changes in the consolidated statement of comprehensive income:        
Cost of reinsurance (5,418.4) (6,004.8)    
Recoveries of incurred claims and other insurance service expenses 3,992.4 4,480.5    
Prior year reserve development and release of risk adjustment on prior year claims (395.4) (218.5)    
Recoveries of insurance service expenses 3,597.0 4,262.0    
Net reinsurance result (1,821.4) (1,742.8)    
Net finance income (expense) from reinsurance contract assets held 563.1 460.9    
Foreign exchange effects 189.9 (189.4)    
Total changes in the consolidated statement of comprehensive income (1,068.4) (1,471.3)    
Cash flows:        
Premiums paid 5,643.6 5,804.4    
Claims and other insurance service expenses recovered (3,939.3) (4,403.2)    
Changes in funds withheld (36.8) (40.4)    
Total changes from cash flows 1,667.5 1,360.8    
Investment components and other (16.9) 6.4    
Contracts recognized on acquisition of subsidiary   (1.3)    
Ending Balance 10,330.5 9,748.3    
Assets for remaining coverage (ARC)        
Cash flows:        
Loss recovery component 1.9 73.4 $ 73.4 $ 23.0
Assets for remaining coverage (ARC) | Reinsurance contracts assets held        
Reinsurance Contract Assets Held        
Beginning Balance (548.7) 180.1    
Changes in the consolidated statement of comprehensive income:        
Cost of reinsurance (5,418.4) (6,004.8)    
Recoveries of incurred claims and other insurance service expenses (1.6) 51.0    
Recoveries of insurance service expenses (1.6) 51.0    
Net reinsurance result (5,420.0) (5,953.8)    
Net finance income (expense) from reinsurance contract assets held 0.5 (0.2)    
Foreign exchange effects (1.9) 7.9    
Total changes in the consolidated statement of comprehensive income (5,421.4) (5,946.1)    
Cash flows:        
Premiums paid 5,643.6 5,804.4    
Changes in funds withheld (5.9) (4.7)    
Total changes from cash flows 5,637.7 5,799.7    
Investment components and other 88.2 (582.4)    
Ending Balance (244.2) (548.7)    
Assets for incurred claims | Estimates of present value of future cash flows | Reinsurance contracts assets held        
Reinsurance Contract Assets Held        
Beginning Balance 9,449.8 8,821.0    
Changes in the consolidated statement of comprehensive income:        
Recoveries of incurred claims and other insurance service expenses 3,684.6 4,123.9    
Prior year reserve development and release of risk adjustment on prior year claims (120.0) 73.4    
Recoveries of insurance service expenses 3,564.6 4,197.3    
Net reinsurance result 3,564.6 4,197.3    
Net finance income (expense) from reinsurance contract assets held 562.6 461.1    
Foreign exchange effects 174.5 (181.6)    
Total changes in the consolidated statement of comprehensive income 4,301.7 4,476.8    
Cash flows:        
Claims and other insurance service expenses recovered (3,939.3) (4,403.2)    
Changes in funds withheld (30.9) (35.7)    
Total changes from cash flows (3,970.2) (4,438.9)    
Investment components and other (122.3) 592.2    
Contracts recognized on acquisition of subsidiary   (1.3)    
Ending Balance 9,659.0 9,449.8    
Assets for incurred claims | Risk adjustment for non-financial risk | Reinsurance contracts assets held        
Reinsurance Contract Assets Held        
Beginning Balance 847.2 852.6    
Changes in the consolidated statement of comprehensive income:        
Recoveries of incurred claims and other insurance service expenses 309.4 305.6    
Prior year reserve development and release of risk adjustment on prior year claims (275.4) (291.9)    
Recoveries of insurance service expenses 34.0 13.7    
Net reinsurance result 34.0 13.7    
Foreign exchange effects 17.3 (15.7)    
Total changes in the consolidated statement of comprehensive income 51.3 (2.0)    
Cash flows:        
Investment components and other 17.2 (3.4)    
Ending Balance 915.7 847.2    
Gulf Insurance        
Cash flows:        
Increase (decrease) in cost of reinsurance   1,301.3    
Increase (decrease) in cost of reinsurance through effects of contracts acquired in period   338.8    
Increase (decrease) in recoveries of reinsurance expenses   1,064.5    
Increase (decrease) in recoveries of reinsurance expenses through effects of acquired contracts   392.9    
Effect of acquired contracts on net reinsurance results   54.1    
Global Insurers and Reinsurers | Reinsurance contracts assets held        
Cash flows:        
Release of risk adjustment for non-financial risk as claims are paid (163.3) (217.4)    
Insurance contracts, favorable (adverse) prior year reserve development 39.9 32.0    
North American Insurers | Reinsurance contracts assets held        
Cash flows:        
Release of risk adjustment for non-financial risk as claims are paid (40.1) (43.2)    
Insurance contracts, favorable (adverse) prior year reserve development 46.2 81.7    
International Insurers and Reinsurers | Reinsurance contracts assets held        
Cash flows:        
Release of risk adjustment for non-financial risk as claims are paid (72.0)      
Insurance contracts, favorable (adverse) prior year reserve development $ (206.1) $ (40.3)