Represents the operating margin assigned to segments for the period.

No definition available.

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- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

No definition available.

+ Details

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- Definition

Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense.

+ References

No definition available.

+ Details

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- Definition

The net result for the period of deducting operating expenses from operating revenues.

+ References

No definition available.

+ Details

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- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

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- Definition

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.

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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Segment Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
Segment Information (Details) - USD ($) $ in Millions	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Number of reportable segments (segments)									2
OPERATING REVENUES	$ 5,323	$ 4,034	$ 4,090	$ 4,209	$ 4,289	$ 4,382	$ 4,398	$ 4,401	$ 17,656	$ 17,470	$ 17,900
Expenses									15,647	15,137	15,321
OPERATING INCOME	$ 524	$ 487	$ 367	$ 631	$ 405	$ 593	$ 647	$ 688	2,009	2,333	2,579
Operating segments (segments)
Segment Reporting Information [Line Items]
OPERATING REVENUES									16,924	16,766	17,171
Expenses									9,390	9,081	9,025
OPERATING INCOME									$ 7,534	$ 7,685	$ 8,146
Margin percentage (percent)									45.00%	46.00%	47.00%
Business
Segment Reporting Information [Line Items]
OPERATING REVENUES									$ 11,220	$ 10,704	$ 10,977
Expenses									6,847	6,391	6,395
OPERATING INCOME									$ 4,373	$ 4,313	$ 4,582
Margin percentage (percent)									39.00%	40.00%	42.00%
Consumer
Segment Reporting Information [Line Items]
OPERATING REVENUES									$ 5,704	$ 6,062	$ 6,194
Expenses									2,543	2,690	2,630
OPERATING INCOME									$ 3,161	$ 3,372	$ 3,564
Margin percentage (percent)									55.00%	56.00%	58.00%