Intangible Assets Including Goodwill - Goodwill by Segment (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
Jun. 30, 2016	Dec. 31, 2015
Changes in Goodwill Balances
Beginning Balance	$ 32,021	$ 30,556
Goodwill Additions	4,137	2,590
Purchase Price Adjustments	5	(3)
Divestitures	(17)	(26)
Foreign Currency Translation and Other Adjustments	276	(1,096)
Ending Balance	36,422	32,021
Goodwill impairment losses	0	0
Goodwill accumulated impairment losses	0	0
Cognitive Solutions
Changes in Goodwill Balances
Beginning Balance	15,621	15,156
Goodwill Additions	3,769	1,020
Purchase Price Adjustments	(3)	(2)
Divestitures	(12)	(18)
Foreign Currency Translation and Other Adjustments	98	(535)
Ending Balance	19,474	15,621
Global Business Services
Changes in Goodwill Balances
Beginning Balance	4,396	4,555
Goodwill Additions	278	74
Purchase Price Adjustments	4	0
Divestitures	(1)	(1)
Foreign Currency Translation and Other Adjustments	12	(232)
Ending Balance	4,689	4,396
Technology Services & Cloud Platforms
Changes in Goodwill Balances
Beginning Balance	10,156	9,373
Goodwill Additions	91	1,087
Purchase Price Adjustments	1	(1)
Divestitures	(5)	(7)
Foreign Currency Translation and Other Adjustments	154	(296)
Ending Balance	10,398	10,156
Systems
Changes in Goodwill Balances
Beginning Balance	1,848	1,472
Goodwill Additions		410
Purchase Price Adjustments	2	0
Foreign Currency Translation and Other Adjustments	11	(33)
Ending Balance	$ 1,861	$ 1,848

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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