Debt - Interest Income/Expense (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of interest paid on debt from continuing and discontinued operations [Line Items]
Interest Paid		$ 268	$ 352	$ 365
Interest Paid, Discontinued Operations		0	20	9
Interest Expense	[1]	252	309	346
Interest Income	[2]	302	330	352
Continuing Operations [Member]
Schedule of interest paid on debt from continuing and discontinued operations [Line Items]
Interest Paid		$ 268	$ 332	$ 356

[1] Includes Equipment financing interest expense, as well as non-financing interest expense included in Other expenses, net in the Consolidated Statements of Income (Loss).

[2] Includes Finance income, as well as other interest income that is included in Other expenses, net in the Consolidated Statements of (Loss) Income.