Goodwill and Other Intangible Assets - Schedule of changes in the net carrying amount of goodwill (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Changes in the net carrying amount of goodwill by operating segment (in millions)
Balance at the beginning of the period	$ 8,358	$ 7,410
Goodwill related to current year acquisitions	38	619
Goodwill related to disposals	(2)	(5)
Goodwill related to prior year acquisitions	4	(13)
Foreign currency translation	(227)	347
Balance at the end of the period	$ 8,171	$ 8,358

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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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of divestiture 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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