Condensed consolidating financial information (Details 1) (USD $) In Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
Condensed Consolidating Statement of Operations
Revenues	$ 11,361.4	[1]	$ 11,288.8	[1]	$ 22,455.9	[1]	$ 22,427.2	[1]
Operating expenses	10,782.1		10,758.5		21,324.2		21,442.2
Operating income	579.3		530.3		1,131.7		985.0
Interest expense, net	(48.8)		(41.5)		(88.1)		(82.6)
Income (loss) before income taxes	530.5		488.8		1,043.6		902.4
Provision for income taxes	196.3		181.5		382.9		334.5
Net income (loss) from continuing operations	334.2		307.3		660.7		567.9
Net loss from discontinued operations, net of tax	0		(17.4)		0		(17.8)
Net income (loss)	334.2		289.9		660.7		550.1
Express Scripts, Inc. [Member]
Condensed Consolidating Statement of Operations
Revenues	7,239.1		7,467.2		14,412.2		14,861.7
Operating expenses	6,820.2		7,051.0		13,545.8		14,102.6
Operating income	418.9		416.2		866.4		759.1
Interest expense, net	(47.5)		(40.1)		(85.4)		(79.7)
Income (loss) before income taxes	371.4		376.1		781.0		679.4
Provision for income taxes	136.4		141.4		283.5		251.7
Net income (loss) from continuing operations	235.0		234.7		497.5		427.7
Equity in earnings of subsidiaries	99.2		55.2		163.2		122.4
Net income (loss)	334.2		289.9		660.7		550.1
Guarantors [Member]
Condensed Consolidating Statement of Operations
Revenues	4,084.2		3,800.1		7,981.4		7,522.8
Operating expenses	3,930.0		3,685.3		7,718.8		7,293.2
Operating income	154.2		114.8		262.6		229.6
Interest expense, net	(1.3)		(1.5)		(3.0)		(3.0)
Income (loss) before income taxes	152.9		113.3		259.6		226.6
Provision for income taxes	58.0		40.4		96.0		83.1
Net income (loss) from continuing operations	94.9		72.9		163.6		143.5
Net income (loss)	94.9		72.9		163.6		143.5
Non-Guarantors [Member]
Condensed Consolidating Statement of Operations
Revenues	38.1		21.5		62.3		42.7
Operating expenses	31.9		22.2		59.6		46.4
Operating income	6.2		(0.7)		2.7		(3.7)
Interest expense, net			0.1		0.3		0.1
Income (loss) before income taxes	6.2		(0.6)		3.0		(3.6)
Provision for income taxes	1.9		(0.3)		3.4		(0.3)
Net income (loss) from continuing operations	4.3		(0.3)		(0.4)		(3.3)
Net loss from discontinued operations, net of tax			(17.4)				(17.8)
Net income (loss)	4.3		(17.7)		(0.4)		(21.1)
Eliminations [Member]
Condensed Consolidating Statement of Operations
Equity in earnings of subsidiaries	(99.2)		(55.2)		(163.2)		(122.4)
Net income (loss)	$ (99.2)		$ (55.2)		$ (163.2)		$ (122.4)

[1] Includes retail pharmacy co-payments of $1,457.1 million and $1,547.3 million for the three months ended June 30, 2011 and 2010, respectively and $2,983.6 million and $3,209.9 million for the six months ended June 30, 2011 and 2010, respectively.