Borrowings - Interest on Debt (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Interest on Debt
Cost of financing	$ 158	$ 138
Interest expense	155	157
Net investment derivative activity	(19)	(10)
Interest capitalized	0	1
Total interest paid and accrued	$ 293	$ 286