Shareholders' equity (Detail) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2022 shares	Dec. 31, 2021 SFr / shares shares	Dec. 31, 2020 SFr / shares shares	Dec. 31, 2019 shares	Jul. 19, 2021 USD ($)	May 31, 2021 $ / shares	Feb. 01, 2021 USD ($)	Nov. 19, 2020 USD ($)	May 31, 2020 $ / shares	Nov. 21, 2019 USD ($)	May 31, 2019 $ / shares	Dec. 01, 2018 USD ($)
Stockholders' Equity Note [Abstract]
Common Stock, Dividend Rate Approved | $ / shares						$ 0.80			$ 0.78		$ 0.75
The number of votes associated with one Common Share		one
Annual dividend per share approved by shareholders | $ / shares						$ 3.20			$ 3.12		$ 3.00
Authorized Share Capital [Line Items]
Common Shares, par value | SFr / shares		SFr 24.15	SFr 24.15
Treasury Stock, Shares, Retired | shares		3,584,150	2,178,600	0
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
2019 Stock Repurchase Plan [Member]
Authorized Share Capital [Line Items]
Stock repurchase program authorized amount | $												$ 1,500
Nov 2019 Stock Repurchase Plan [Member]
Authorized Share Capital [Line Items]
Stock repurchase program authorized amount | $										$ 1,500
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
July 2021 Stock Repurchase Plan
Authorized Share Capital [Line Items]
Stock repurchase program authorized amount | $					$ 5,000
Subsequent Event [Member]
Authorized Share Capital [Line Items]
Treasury Stock, Shares, Retired | shares	14,465,400