Income and Other Taxes - Allocation of Income Tax Expense Benefit (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Interperiod Allocaion [Line Items]
Income tax expense	$ 64	$ 179	$ 247
Discontinued operations	0	95	10
Total Income Tax Expense	105	226	420
Changes in defined benefit plans
Income Tax Interperiod Allocaion [Line Items]
Other comprehensive income (loss), tax	43	(55)	131
Cash flow hedges
Income Tax Interperiod Allocaion [Line Items]
Other comprehensive income (loss), tax	1	(1)	5
Translation adjustments
Income Tax Interperiod Allocaion [Line Items]
Other comprehensive income (loss), tax	(3)	8	(9)
Retained Earnings
Income Tax Interperiod Allocaion [Line Items]
Other comprehensive income (loss), tax	$ 0	$ 0	$ 36