v3.25.4
Insurance Contract Liabilities - Estimates of undiscounted cumulative claims (Details) - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Estimates of undiscounted gross cumulative claims                  
Insurance Contract Liabilities                  
Property and casualty provision for losses and loss adjustment expenses $ 48,221.2 $ 44,110.0 $ 41,221.8 $ 36,306.4 $ 32,329.1 $ 28,700.5 $ 26,528.3 $ 25,426.9 $ 25,284.5
Favourable (adverse) development   (35.8) 83.0 (1,023.3) (1,174.7) (1,436.0) (1,455.0) (1,501.1) (49.2)
Estimates of undiscounted gross cumulative claims | Effect of foreign currency translation                  
Insurance Contract Liabilities                  
Favourable (adverse) development   (500.4) 135.8 (2.9) 141.3 234.9 230.4 93.4 254.7
Estimates of undiscounted gross cumulative claims | Favourable (adverse) loss reserve development                  
Insurance Contract Liabilities                  
Favourable (adverse) development   464.6 (52.8) (1,020.4) (1,316.0) (1,670.9) (1,685.4) (1,594.5) (303.9)
Estimates of undiscounted gross cumulative claims | One year later                  
Insurance Contract Liabilities                  
Cumulative payments   12,061.2 11,386.6 10,341.7 8,410.7 6,986.7 7,018.7 7,191.0 6,917.3
Reserves re-estimated   44,145.8 40,421.4 36,470.5 31,640.8 28,119.8 26,259.1 25,256.3 24,131.2
Estimates of undiscounted gross cumulative claims | Two years later                  
Insurance Contract Liabilities                  
Cumulative payments     18,995.0 17,308.6 14,571.5 11,990.6 11,133.7 11,487.9 11,052.3
Reserves re-estimated     41,138.8 36,493.3 32,041.6 27,894.1 26,052.6 25,124.0 24,091.7
Estimates of undiscounted gross cumulative claims | Three years later                  
Insurance Contract Liabilities                  
Cumulative payments       22,368.9 19,487.3 16,410.5 14,702.8 14,318.9 13,928.6
Reserves re-estimated       37,329.7 32,525.5 28,468.4 25,961.4 25,132.6 23,949.9
Estimates of undiscounted gross cumulative claims | Four years later                  
Insurance Contract Liabilities                  
Cumulative payments         22,968.0 19,797.6 17,959.2 16,807.6 15,843.4
Reserves re-estimated         33,503.8 29,118.6 26,611.8 25,286.7 24,046.1
Estimates of undiscounted gross cumulative claims | Five years later                  
Insurance Contract Liabilities                  
Cumulative payments           22,304.0 20,332.7 19,121.9 17,528.7
Reserves re-estimated           30,136.5 27,152.9 25,851.6 24,202.6
Estimates of undiscounted gross cumulative claims | Six years later                  
Insurance Contract Liabilities                  
Cumulative payments             22,133.7 20,755.7 19,141.7
Reserves re-estimated             27,983.3 26,226.1 24,554.7
Estimates of undiscounted gross cumulative claims | Seven years later                  
Insurance Contract Liabilities                  
Cumulative payments               22,128.5 20,301.2
Reserves re-estimated               26,928.0 24,824.2
Estimates of undiscounted gross cumulative claims | Eight years later                  
Insurance Contract Liabilities                  
Cumulative payments                 21,289.1
Reserves re-estimated                 25,333.7
Estimates of undiscounted net cumulative claims                  
Insurance Contract Liabilities                  
Property and casualty provision for losses and loss adjustment expenses $ 37,865.6 34,197.6 31,618.1 27,800.1 24,068.6 21,468.6 19,858.9 19,334.7 19,750.1
Favourable (adverse) development   (69.6) 153.5 (506.0) (1,286.7) (1,476.1) (1,393.3) (977.4) 411.0
Estimates of undiscounted net cumulative claims | Effect of foreign currency translation                  
Insurance Contract Liabilities                  
Favourable (adverse) development   (435.3) 94.5 (20.1) 143.4 111.8 87.8 (22.3) 125.8
Estimates of undiscounted net cumulative claims | Favourable (adverse) loss reserve development                  
Insurance Contract Liabilities                  
Favourable (adverse) development   365.7 59.0 (485.9) (1,430.1) (1,587.9) (1,481.1) (955.1) 285.2
Estimates of undiscounted net cumulative claims | One year later                  
Insurance Contract Liabilities                  
Cumulative payments   9,227.9 8,508.8 7,791.6 6,415.3 5,426.1 5,339.8 5,407.0 5,297.4
Reserves re-estimated   $ 34,267.2 30,843.5 27,534.6 23,808.7 21,233.4 19,587.2 19,052.8 18,642.9
Estimates of undiscounted net cumulative claims | Two years later                  
Insurance Contract Liabilities                  
Cumulative payments     14,318.1 13,108.6 11,042.3 9,269.8 8,480.3 8,606.4 8,394.6
Reserves re-estimated     $ 31,464.6 27,593.1 24,151.8 21,342.5 19,585.7 18,937.4 18,411.4
Estimates of undiscounted net cumulative claims | Three years later                  
Insurance Contract Liabilities                  
Cumulative payments       16,975.5 14,770.8 12,456.8 11,216.3 10,719.0 10,562.7
Reserves re-estimated       $ 28,306.1 24,570.4 21,728.2 19,845.5 19,052.3 18,275.8
Estimates of undiscounted net cumulative claims | Four years later                  
Insurance Contract Liabilities                  
Cumulative payments         17,406.7 14,979.6 13,473.3 12,624.3 12,010.0
Reserves re-estimated         $ 25,355.3 22,194.9 20,269.4 19,227.2 18,392.0
Estimates of undiscounted net cumulative claims | Five years later                  
Insurance Contract Liabilities                  
Cumulative payments           16,854.8 15,227.4 14,142.2 13,291.3
Reserves re-estimated           $ 22,944.7 20,657.3 19,589.3 18,589.3
Estimates of undiscounted net cumulative claims | Six years later                  
Insurance Contract Liabilities                  
Cumulative payments             16,579.7 15,378.5 14,348.9
Reserves re-estimated             $ 21,252.2 19,891.7 18,839.6
Estimates of undiscounted net cumulative claims | Seven years later                  
Insurance Contract Liabilities                  
Cumulative payments               16,416.0 15,221.8
Reserves re-estimated               $ 20,312.1 19,059.1
Estimates of undiscounted net cumulative claims | Eight years later                  
Insurance Contract Liabilities                  
Cumulative payments                 15,979.0
Reserves re-estimated                 $ 19,339.1