Income and Other Taxes - Allocation of Income Tax Expense Benefit (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Interperiod Allocaion [Line Items]
Pre-tax income		$ 257	$ 481	$ 62
Discontinued Operation, Tax Effect of Discontinued Operation	[1]	0	(12)	(250)
Retained Earnings	[2]	36	0	0
Total Income Tax Expense (Benefit)		420	538	(179)
Changes in defined benefit plans
Income Tax Interperiod Allocaion [Line Items]
Other comprehensive income (loss), tax		131	63	15
Cash flow hedges
Income Tax Interperiod Allocaion [Line Items]
Other comprehensive income (loss), tax		5	5	(8)
Translation adjustments
Income Tax Interperiod Allocaion [Line Items]
Other comprehensive income (loss), tax		$ (9)	$ 1	$ 2

[1] Refer to Note 5 - Divestitures for additional information regarding discontinued operations.

[2] Refer to Note 2 - Revenue for additional information regarding our adoption of ASU 2014-09.