Changes in Business (Details) (USD $) In Billions, except Per Share data, unless otherwise specified	Jul. 20, 2011
Changes In Business (Textuals) [Abstract]
Total consideration for Medco shareholders	$ 23.2
Cash and stock paid per share for Medco shareholders	$ 58.83
Cash paid per share for Medco shareholders	$ 28.80
Stock paid per share for Medco shareholders	$ 0.81
Express Scripts, Inc. [Member]
Business Acquisition [Line Items]
Percentage of voting rights company owned	60.00%
Medco [Member]
Business Acquisition [Line Items]
Percentage of voting rights company owned	40.00%

Business Acquisition Cost Of Acquired Entity Cash Paid Per Share.

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Business Acquisition Purchase Consideration Payable In Cash Per Share.

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Business Acquisition Purchase Consideration Payable In Stock Per Share.

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- Definition

Changes in business.

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The total cost of the acquired entity including the cash paid to shareholders of acquired entities, fair value of debt and equity securities issued to shareholders of acquired entities, the fair value of the liabilities assumed, and direct costs of the acquisition.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 51

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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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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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Percentage of voting equity interests acquired in the business combination.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 68

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6909870&loc=d3e1392-128463

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