Basis of Presentation - Reclassification (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net cash provided by operating activities	$ 3,955	$ 5,530	[1],[2]
Net cash (used in)/provided by investing activities	350	(1,886)	[2]
Total cash flows	$ 2,270	6,668
Reclassification of certain financing receivables
Net cash provided by operating activities		(142)
Net cash (used in)/provided by investing activities		142
Total cash flows		$ 0

[1] Reclassified to reflect adoption of the FASB guidance on share-based compensation.

[2] Revised classification of certain financing receivables.