Summary of Significant Accounting Policies - Revenue Recognition (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended	3 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Change in Recognition of Refund or Chargeback Reserve
Accounting Policies [Abstract]
Advertising	$ 4,279	$ 3,154	$ 1,868
Payments and other fees	810	557	106
Total revenue	$ 5,089	$ 3,711	$ 1,974
Payment transaction claim, term	30 days
Change in Accounting Estimate
Change in accounting estimate, financial effect				66

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Revenue from the sale of advertising time (such as television and radio) or space (newspaper or magazine pages). May also include advertising, marketing and promotional services rendered during the reporting period.

+ References

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- Definition

Disclosure of the effect on income from continuing operations, net income (or other appropriate captions of changes in applicable net assets or performance indicator), and any related per-share amounts of the current period when a change in accounting estimate affects several future periods.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 250

-SubTopic 10

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6801783&loc=d3e22595-107794

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 270

-SubTopic 10

-Section 45

-Paragraph 14

-URI http://asc.fasb.org/extlink&oid=6372559&loc=d3e777-108305

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 154

-Paragraph 22

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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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- Definition

Revenues from the sale of other goods or rendering of other services, not elsewhere specified in the taxonomy; net of (reduced by) sales adjustments, returns, allowances, and discounts.

+ 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(a),(d))

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

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-Name Regulation S-X (SX)

-Number 210

-Section 03

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Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains.

+ 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=6880815&loc=d3e20235-122688

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-Publisher SEC

-Name Regulation S-X (SX)

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