Share-Based Compensation Plans - Share-based compensation expense recognized in continuing operations (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 312	$ 317	$ 338
Tax benefit	61	66	74
Share-based compensation expense, net of tax	251	251	264
Employee share purchase plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	10	9	9
Restricted share units (“RSUs”)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	186	198	186
Performance share awards (“PSAs”)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 116	$ 110	$ 143

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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