Debt - Interest Income and Expense (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Debt Disclosure [Abstract]
Interest expense	[1]	$ 57	$ 74	$ 126	$ 161
Interest income	[2]	$ 76	$ 84	$ 154	$ 168

[1] Includes Cost of financing as well as non-financing interest expense that is included in Other expenses, net in the Condensed Consolidated Statements of Income.

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