Shareholders' equity Repurchase of Common Shares (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Feb. 23, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased		27,644,500	3,584,150	10,442,238
2019 Stock Repurchase Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased				10,442,238
Common Shares repurchased				$ 1,531
Nov 2019 Stock Repurchase Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased			3,584,150
Common Shares repurchased			$ 516
Nov 2020 Stock Repurchase Plan [Member]
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased		27,644,500
Common Shares repurchased		$ 4,861
Subsequent Event [Member] | July 2021 Stock Repurchase Plan
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased	1,966,600
Common Shares repurchased	$ 405