Shareholders' equity (Detail) SFr / shares in Units, $ / shares in Units, $ in Millions					12 Months Ended
	May 21, 2024 shares	May 22, 2023 shares	Aug. 04, 2022 shares	Jan. 17, 2022 shares	Dec. 31, 2024 CHF (SFr) SFr / shares shares	Dec. 31, 2023 SFr / shares shares	Dec. 31, 2022 shares	May 16, 2024 $ / shares	May 19, 2023 $ / shares	May 31, 2022 $ / shares	May 19, 2022 USD ($)	Jul. 19, 2021 USD ($)
Stockholders' Equity Note [Abstract]
Common Stock, Dividend Rate Approved | $ / shares								$ 0.91	$ 0.86	$ 0.83
The number of votes associated with one Common Share					one
Annual dividend per share approved by shareholders | $ / shares								$ 3.64	$ 3.44	$ 3.32
Authorized Share Capital [Line Items]
Common Shares, par value | SFr / shares					SFr 0.50	SFr 0.50
Treasury Stock, Shares, Retired	11,825,600	14,925,028	13,179,100	14,465,400	11,825,600	14,925,028	27,644,500
The maximum ownership percentage for voting allowed for any one shareholder					10.00%
CB_Capital Band Increase Decrease Percentage					20.00%
Issuance of Debt
Authorized Share Capital [Line Items]
Authorized share capital for future issuance					33,000,000
Employee Benefit Plans
Authorized Share Capital [Line Items]
Authorized share capital for future issuance					25,410,929
Capital Band Upper Limit
Authorized Share Capital [Line Items]
Authorized share capital for future issuance					503,551,183
Share capital increases and reductions | SFr					SFr 251,775,591.5
Capital Band Lower Limit
Authorized Share Capital [Line Items]
Authorized share capital for future issuance					335,700,789
Share capital increases and reductions | SFr					SFr 167,850,394.5
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