Goodwill and Other Intangible Assets - Schedule of other intangible assets by asset class (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives, gross carrying amount	$ 4,446	$ 4,542
Intangible assets with finite lives, accumulated amortization	2,266	2,022
Intangible assets, net	2,180	2,520
Amortization expense on intangible assets	314	352	$ 395
Tradenames [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives, gross carrying amount	1,019	1,019
Intangible assets with finite lives, accumulated amortization	0	0
Intangible assets, net	1,019	1,019
Customer related and contract based [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives, gross carrying amount	2,886	2,952
Intangible assets with finite lives, accumulated amortization	1,809	1,579
Intangible assets, net	1,077	1,373
Technology and other [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets with finite lives, gross carrying amount	541	571
Intangible assets with finite lives, accumulated amortization	457	443
Intangible assets, net	$ 84	$ 128