Shareholders' equity (Detail) $ / shares in Units, $ in Millions					12 Months Ended
	May 22, 2023 shares	Aug. 04, 2022 shares	Jan. 17, 2022 shares	Aug. 04, 2021 shares	Dec. 31, 2023 SFr / shares shares	Dec. 31, 2022 SFr / shares shares	Dec. 31, 2021 shares	May 19, 2023 $ / shares	May 31, 2022 $ / shares	May 19, 2022 USD ($)	Jul. 19, 2021 USD ($)	May 31, 2021 $ / shares	Feb. 01, 2021 USD ($)	Nov. 19, 2020 USD ($)
Stockholders' Equity Note [Abstract]
Common Stock, Dividend Rate Approved | $ / shares								$ 0.86	$ 0.83			$ 0.80
The number of votes associated with one Common Share					one
Annual dividend per share approved by shareholders | $ / shares								$ 3.44	$ 3.32			$ 3.20
Authorized Share Capital [Line Items]
Common Shares, par value | SFr / shares					SFr 0.50	SFr 24.15
Treasury Stock, Shares, Retired | shares	14,925,028	13,179,100	14,465,400	3,584,150	14,925,028	27,644,500	3,584,150
The maximum ownership percentage for voting allowed for any one shareholder					10.00%
General Purpose
Authorized Share Capital [Line Items]
Authorized share capital for future issuance | shares					200,000,000
Issuance of Debt
Authorized Share Capital [Line Items]
Authorized share capital for future issuance | shares					33,000,000
Employee Benefit Plans
Authorized Share Capital [Line Items]
Authorized share capital for future issuance | shares					25,410,929
Nov 2020 Stock Repurchase Plan [Member]
Authorized Share Capital [Line Items]
Stock repurchase program authorized amount | $													$ 2,500	$ 1,500
CB_Increase(Decrease)StockRepurchaseProgramAuthorizedAmount | $													$ 1,000
2022 Stock Repurchase Plan
Authorized Share Capital [Line Items]
Stock repurchase program authorized amount | $										$ 2,500
2021 Stock Repurchase Plan
Authorized Share Capital [Line Items]
Stock repurchase program authorized amount | $											$ 5,000