Shareholders' equity Share Repurchases (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Jul. 01, 2023	May 19, 2022	Jul. 19, 2021
July 2021 Stock Repurchase Plan
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount								$ 5,000
Number of shares repurchased			5,476,300		10,346,200
Cost of shares repurchased			$ 1,129		$ 2,130
Repurchase authorization remaining at end of period (1)			$ 2,500		$ 2,500
May 2022 Stock Repurchase Plan
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount							$ 2,500
Number of shares repurchased		3,674,300		5,684,700
Cost of shares repurchased		$ 724		$ 1,152
Repurchase authorization remaining at end of period (1)	[1]	0		0
CB_Stock Repurchase Program_Authorized Repurchase_Expired Amount		$ 474		$ 474
July 2023 Stock Repurchase Plan
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount						$ 5,000

[1] As of June 30, 2023, $474 million expired under the May 2022 $2.5 billion share repurchase authorization.