Consolidated Statement of Operations (Unaudited) (Parenthetical) (USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Consolidated Statement of Operations [Abstract]
Retail pharmacy co-payments included in Network revenues	$ 1,457.1	$ 1,547.3	$ 2,983.6	$ 3,209.9

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esrx_RetailPharmacyCoPaymentsIncludedInNetworkRevenues

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duration