Goodwill and Intangible Assets - Goodwill Balances and Adjustments (Details) $ in Millions	12 Months Ended
Dec. 31, 2018 USD ($) acquisition	Dec. 31, 2017 USD ($) business	Dec. 31, 2016 USD ($) business
Total Goodwill
Beginning balance	$ 4,339	$ 4,059
Goodwill Acquired	1,981	276
Adjustments	(36)	4
Ending balance	$ 6,284	$ 4,339	$ 4,059
Number of businesses acquired	4	2	0

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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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 increase (decrease) from foreign currency translation adjustments and purchase accounting adjustments 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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The number of businesses acquired by the entity during the period.

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