The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4297-108586

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The amount of the unrecognized tax benefit of a position taken for which it is reasonably possible that the total amount thereof will significantly increase or decrease within twelve months of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (d)
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-SubTopic 10
-Section 50
-Paragraph 15A
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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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-Name Accounting Standards Codification
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Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Income Taxes (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Net income tax payments/(refunds)	$ 896	$ 1,460	$ 1,490
Unrecognized tax benefits that would affect the effective tax rate, if recognized	1,568	1,402	1,479
Unrecognized tax benefits	1,736	$ 1,557	$ 1,617	$ 1,312
United States [member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	540
State and Local Jurisdiction [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	$ 430