Goodwill and Other Intangible Assets - Schedule of other intangible assets by asset class (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives, gross carrying amount	$ 4,680	$ 4,446
Intangible assets with finite lives, accumulated amortization	2,457	2,266
Intangible assets, net	2,223	2,180
Amortization expense on intangible assets	277	314	$ 352
Tradenames
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives, gross carrying amount	998	1,019
Intangible assets with finite lives, accumulated amortization	0	0
Intangible assets, net	998	1,019
Customer related and contract based
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives, gross carrying amount	3,108	2,886
Intangible assets with finite lives, accumulated amortization	1,971	1,809
Intangible assets, net	1,137	1,077
Technology and other
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives, gross carrying amount	574	541
Intangible assets with finite lives, accumulated amortization	486	457
Intangible assets, net	$ 88	$ 84