Goodwill and Other Intangibles - Changes in Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Beginning balance, Goodwill	$ 20,086	$ 20,257
Beginning balance, Accumulated impairment losses	(3,240)	(3,240)
Beginning balance, Net goodwill	16,846	17,017
Acquisitions	5	55
Dispositions	(25)
Other adjustments (primarily foreign currency)	(130)	(226)
Ending balance, Goodwill	19,936	20,086
Ending balance, Accumulated impairment losses	(3,240)	(3,240)
Ending balance, Net goodwill	16,696	16,846
Divested Operations
Goodwill [Roll Forward]
Beginning balance, Goodwill	181	181
Beginning balance, Accumulated impairment losses	(181)	(181)
Beginning balance, Net goodwill	0	0
Acquisitions	0	0
Dispositions	0
Other adjustments (primarily foreign currency)	0	0
Ending balance, Goodwill	181	181
Ending balance, Accumulated impairment losses	(181)	(181)
Ending balance, Net goodwill	0	0
Operating Segments | Global Business Solutions
Goodwill [Roll Forward]
Beginning balance, Goodwill	15,567	15,712
Beginning balance, Accumulated impairment losses	(1,363)	(1,363)
Beginning balance, Net goodwill	14,204	14,349
Acquisitions	5	9
Dispositions	(25)
Other adjustments (primarily foreign currency)	(42)	(154)
Ending balance, Goodwill	15,505	15,567
Ending balance, Accumulated impairment losses	(1,363)	(1,363)
Ending balance, Net goodwill	14,142	14,204
Operating Segments | Global Financial Solutions
Goodwill [Roll Forward]
Beginning balance, Goodwill	2,054	2,126
Beginning balance, Accumulated impairment losses	(683)	(683)
Beginning balance, Net goodwill	1,371	1,443
Acquisitions	0	0
Dispositions	0
Other adjustments (primarily foreign currency)	(88)	(72)
Ending balance, Goodwill	1,966	2,054
Ending balance, Accumulated impairment losses	(683)	(683)
Ending balance, Net goodwill	1,283	1,371
Operating Segments | Network & Security Solutions
Goodwill [Roll Forward]
Beginning balance, Goodwill	2,284	2,238
Beginning balance, Accumulated impairment losses	(1,013)	(1,013)
Beginning balance, Net goodwill	1,271	1,225
Acquisitions	0	46
Dispositions	0
Other adjustments (primarily foreign currency)	0	0
Ending balance, Goodwill	2,284	2,284
Ending balance, Accumulated impairment losses	(1,013)	(1,013)
Ending balance, Net goodwill	$ 1,271	$ 1,271