Income Taxes - Undistributed Earnings and Foreign Location Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes.
Income tax benefits attributable to reduced tax rates or exemptions in foreign locations	$ 228	$ 142	$ 114
EPS impact of reduced tax rates or exemptions in foreign locations (in dollars per diluted share)	$ 0.37	$ 0.23	$ 0.18
Undistributed earnings of non-U.S. subsidiaries	$ 15,000

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- Definition

The amount of income taxes from which a reporting entity is exempt or for which it will receive a reduction in income taxes as a result of the income tax holiday granted by the taxing jurisdiction.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-URI http://asc.fasb.org/extlink&oid=34349781&loc=d3e330215-122817

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- Definition

Per share amount effect of the income tax benefit resulting from the income tax holidays granted by taxing jurisdictions.

+ References

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- Definition

Amount of undistributed earnings of foreign subsidiaries intended to be permanently reinvested outside the country of domicile.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 740
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6487024&loc=d3e29054-158556

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 740
-Section 50
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-URI http://asc.fasb.org/extlink&oid=6479915&loc=d3e66715-112838

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-Publisher FASB
-Name Accounting Standards Codification
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