Share-based compensation (Pre-tax and After-tax Share-based Compensation Expense) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based Payment Arrangement, Expense, Tax Benefit		$ 19	$ 29	$ 19
Restricted stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense, pre-tax		253	230	210
Share-based compensation expense, after-tax		202	179	164
Stock options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense, pre-tax		71	60	55
Share-based compensation expense, after-tax	[1]	$ 56	$ 38	$ 36

[1] The windfall tax benefit recorded to Income tax expense in the Consolidated statement of operations was $19 million, $29 million, and $19 million for the years ended December 31, 2023, 2022, and 2021, respectively.