Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 segment	Sep. 30, 2011
Segment information
Expenses	$ 3,835	$ 4,048	$ 11,746	$ 9,206
Net income	736	548	2,047	1,492
Number of operating segments			4
Operating segments
Segment information
Revenues	4,314	4,349	13,004	10,072
Expenses	2,037	2,043	6,039	4,428
Net income	2,277	2,306	6,965	5,644
Margin percentage	53.00%	53.00%	54.00%	56.00%
Regional markets
Segment information
Number of regions in which the entity operates	6		6
Revenues	2,468	2,522	7,431	6,199
Expenses	1,079	1,092	3,158	2,592
Net income	1,389	1,430	4,273	3,607
Margin percentage	56.00%	57.00%	58.00%	58.00%
Wholesale markets
Segment information
Revenues	908	982	2,813	2,344
Expenses	273	307	846	708
Net income	635	675	1,967	1,636
Margin percentage	70.00%	69.00%	70.00%	70.00%
Enterprise markets - network
Segment information
Revenues	658	622	1,938	1,298
Expenses	466	479	1,402	961
Net income	192	143	536	337
Margin percentage	29.00%	23.00%	28.00%	26.00%
Enterprise markets - data hosting
Segment information
Revenues	280	223	822	231
Expenses	219	165	633	167
Net income	$ 61	$ 58	$ 189	$ 64
Margin percentage	22.00%	26.00%	23.00%	28.00%

Represents the number of regions in which the entity operates.

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- Definition

Represents the operating margin assigned to segments for the period.

+ References

No definition available.

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- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

No definition available.

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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.

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- Details

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- Definition

Amount of total revenue for the reportable segments, including revenue from external customers, transactions with other operating segments of the same entity, and (gross) interest revenue. All considered to be "operating revenue" for purposes of the taxonomy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 22

-Subparagraph (a),(b),(c)

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8736-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 27

-Subparagraph a, b, c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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