Goodwill and Other Intangibles - Changes in Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Gross goodwill at beginning of period	$ 20,257	$ 20,488
Accumulated impairment losses at beginning of period	(3,240)	(3,240)
Goodwill at beginning of period	17,017	17,248
Acquisitions	55	33
Other adjustments (primarily foreign currency)	(226)	(264)
Gross goodwill at end of period	20,086	20,257
Accumulated impairment losses at end of period	(3,240)	(3,240)
Goodwill at end of period	16,846	17,017
Operating segments | Global Business Solutions
Goodwill [Roll Forward]
Gross goodwill at beginning of period	15,712	15,892
Accumulated impairment losses at beginning of period	(1,363)	(1,363)
Goodwill at beginning of period	14,349	14,529
Acquisitions	9	0
Other adjustments (primarily foreign currency)	(154)	(180)
Gross goodwill at end of period	15,567	15,712
Accumulated impairment losses at end of period	(1,363)	(1,363)
Goodwill at end of period	14,204	14,349
Operating segments | Global Financial Solutions
Goodwill [Roll Forward]
Gross goodwill at beginning of period	2,126	2,210
Accumulated impairment losses at beginning of period	(683)	(683)
Goodwill at beginning of period	1,443	1,527
Acquisitions	0	0
Other adjustments (primarily foreign currency)	(72)	(84)
Gross goodwill at end of period	2,054	2,126
Accumulated impairment losses at end of period	(683)	(683)
Goodwill at end of period	1,371	1,443
Operating segments | Network & Security Solutions
Goodwill [Roll Forward]
Gross goodwill at beginning of period	2,238	2,205
Accumulated impairment losses at beginning of period	(1,013)	(1,013)
Goodwill at beginning of period	1,225	1,192
Acquisitions	46	33
Other adjustments (primarily foreign currency)	0	0
Gross goodwill at end of period	2,284	2,238
Accumulated impairment losses at end of period	(1,013)	(1,013)
Goodwill at end of period	1,271	1,225
Divested Operations
Goodwill [Roll Forward]
Gross goodwill at beginning of period	181	181
Accumulated impairment losses at beginning of period	(181)	(181)
Goodwill at beginning of period	0	0
Acquisitions	0	0
Other adjustments (primarily foreign currency)	0	0
Gross goodwill at end of period	181	181
Accumulated impairment losses at end of period	(181)	(181)
Goodwill at end of period	$ 0	$ 0