Restructuring Charges (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Type of Restructuring [Domain]
Restructuring Charges
Beginning Balance			$ 470	$ 233	$ 470
Restructuring charges, net of revisions	$ 313	$ 133	(26)	411	(4)
Payments			(155)	(115)	(229)
Other non-cash			(28)	(59)	(4)
Ending Balance	470		261	470	233
Employee Severance [Member]
Restructuring Charges
Beginning Balance			435	196	412
Restructuring charges, net of revisions			(33)	383	(7)
Payments			(141)	(93)	(206)
Other non-cash			(23)	(51)	(3)
Ending Balance	435		238	435	196
Other Terminations [Member]
Restructuring Charges
Beginning Balance			35	37	58
Restructuring charges, net of revisions			7	28	3
Payments			(14)	(22)	(23)
Other non-cash			(5)	(8)	(1)
Ending Balance	$ 35		$ 23	35	$ 37
GBT JV [Member]
Restructuring Charges
Other non-cash				(42)
Foreign exchange and other non-cash charges
Restructuring Charges
Other non-cash				$ (17)