Condensed consolidating financial information (Details 2) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Condensed Consolidating Statement of Cash Flows
Net cash flows provided by (used in) operating activities			$ 703,100,000	$ 1,448,800,000
Cash flows from investing activities:
Purchases of property and equipment	(34,600,000)	(17,400,000)	(54,100,000)	(51,100,000)
Other			2,400,000	2,700,000
Net cash used in investing activities - continuing operations			(51,700,000)	(48,400,000)
Net cash used in investing activities - discontinued operations				(800,000)
Net cash used in investing activities			(51,700,000)	(49,200,000)
Cash flows from financing activities:
Treasury stock acquired			(2,515,700,000)	(528,700,000)
Proceeds from long-term debt, net of discounts			1,494,000,000
Proceeds from revolving credit line, net			100,000,000
Repayment of long-term debt			(100,000)	(360,000,000)
Tax benefit relating to employee stock compensation			25,900,000	30,800,000
Net proceeds from employee stock plans			23,100,000	16,700,000
Deferred financing fees			(10,900,000)
Net cash (used in) provided by financing activities			(883,700,000)	(841,200,000)
Effect of foreign currency translation adjustment			(400,000)	2,400,000
Net (decrease) increase in cash and cash equivalents			(232,700,000)	560,800,000
Cash and cash equivalents at beginning of period			523,700,000	1,070,400,000
Cash and cash equivalents at end of period	291,000,000	1,631,200,000	291,000,000	1,631,200,000
Express Scripts, Inc. [Member]
Condensed Consolidating Statement of Cash Flows
Net cash flows provided by (used in) operating activities			573,200,000	977,900,000
Cash flows from investing activities:
Purchases of property and equipment			(46,200,000)	(29,200,000)
Other				11,600,000
Net cash used in investing activities - continuing operations				(17,600,000)
Net cash used in investing activities			(46,200,000)	(17,600,000)
Cash flows from financing activities:
Treasury stock acquired			(2,515,700,000)	(528,700,000)
Proceeds from long-term debt, net of discounts			1,494,000,000
Proceeds from revolving credit line, net			100,000,000
Repayment of long-term debt			(100,000)	(360,000,000)
Tax benefit relating to employee stock compensation			25,900,000	30,800,000
Net proceeds from employee stock plans			23,100,000	16,700,000
Deferred financing fees			(10,900,000)
Net transactions with parent			98,700,000	445,600,000
Net cash (used in) provided by financing activities			(785,000,000)	(395,600,000)
Net (decrease) increase in cash and cash equivalents			(258,000,000)	564,700,000
Cash and cash equivalents at beginning of period			456,700,000	1,005,000,000
Cash and cash equivalents at end of period	198,700,000	1,569,700,000	198,700,000	1,569,700,000
Guarantors [Member]
Condensed Consolidating Statement of Cash Flows
Net cash flows provided by (used in) operating activities			295,600,000	589,300,000
Cash flows from investing activities:
Purchases of property and equipment			(4,100,000)	(21,400,000)
Other			2,100,000	(1,900,000)
Net cash used in investing activities - continuing operations				(23,300,000)
Net cash used in investing activities			(2,000,000)	(23,300,000)
Cash flows from financing activities:
Net transactions with parent			(299,400,000)	(567,500,000)
Net cash (used in) provided by financing activities			(299,400,000)	(567,500,000)
Net (decrease) increase in cash and cash equivalents			(5,800,000)	(1,500,000)
Cash and cash equivalents at beginning of period			9,000,000	10,000,000
Cash and cash equivalents at end of period	3,200,000	8,500,000	3,200,000	8,500,000
Non-Guarantors [Member]
Condensed Consolidating Statement of Cash Flows
Net cash flows provided by (used in) operating activities			(2,500,000)	4,000,000
Cash flows from investing activities:
Purchases of property and equipment			(3,800,000)	(500,000)
Other			300,000	(7,000,000)
Net cash used in investing activities - continuing operations				(7,500,000)
Net cash used in investing activities - discontinued operations				(800,000)
Net cash used in investing activities			(3,500,000)	(8,300,000)
Cash flows from financing activities:
Net transactions with parent			37,500,000	(500,000)
Net cash (used in) provided by financing activities			37,500,000	(500,000)
Effect of foreign currency translation adjustment			(400,000)	2,400,000
Net (decrease) increase in cash and cash equivalents			31,100,000	(2,400,000)
Cash and cash equivalents at beginning of period			58,000,000	55,400,000
Cash and cash equivalents at end of period	89,100,000	53,000,000	89,100,000	53,000,000
Eliminations [Member]
Condensed Consolidating Statement of Cash Flows
Net cash flows provided by (used in) operating activities			(163,200,000)	(122,400,000)
Cash flows from financing activities:
Net transactions with parent			163,200,000	122,400,000
Net cash (used in) provided by financing activities			163,200,000	122,400,000
Cash and cash equivalents at beginning of period			0
Cash and cash equivalents at end of period	$ 0		$ 0