Segment Information (Schedule of Segment Information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Segment Reporting Information [Line Items]
Segment Reporting Revenue From External Customers	$ 32,954		$ 29,755		$ 65,162		$ 60,454
Interest Expense	(59)		(55)		(118)		(111)
Income Before Income Taxes from Continuing Operations	629		561		1,223		1,089
Reportable Segment [Member]
Segment Reporting Information [Line Items]
Operating profit (2) (3) (4) (5)	798		713		1,536		1,303
Distribution Solutions [Member]
Segment Reporting Information [Line Items]
Segment Reporting Revenue From External Customers	32,169	[1]	29,026	[1]	63,572	[1]	58,986	[1]
Operating profit (2) (3) (4) (5)	685	[2],[3]	621	[2],[3],[4]	1,304	[2],[3],[4]	1,121	[2],[3],[4]
Distribution Solutions Domestic Pharmaceutical Distribution And Services [Member]
Segment Reporting Information [Line Items]
Segment Reporting Revenue From External Customers	28,069		25,744		55,549		52,392
Distribution Solutions Direct Distribution And Services [Member]
Segment Reporting Information [Line Items]
Segment Reporting Revenue From External Customers	23,729		20,938		46,761		42,239
Distribution Solutions Sales To Customers Warehouses [Member]
Segment Reporting Information [Line Items]
Segment Reporting Revenue From External Customers	4,340		4,806		8,788		10,153
Distribution Solutions Canada Pharmaceutical Distribution And Services [Member]
Segment Reporting Information [Line Items]
Segment Reporting Revenue From External Customers	2,633		2,409		5,199		4,926
Distribution Solutions Medical Surgical Distribution And Services [Member]
Segment Reporting Information [Line Items]
Segment Reporting Revenue From External Customers	1,467		873		2,824		1,668
Technology Solutions [Member]
Segment Reporting Information [Line Items]
Segment Reporting Revenue From External Customers	785		729		1,590		1,468
Operating profit (2) (3) (4) (5)	113		92		232		182
Technology Solutions Services [Member]
Segment Reporting Information [Line Items]
Segment Reporting Revenue From External Customers	656		585		1,317		1,179
Technology Solutions Software [Member]
Segment Reporting Information [Line Items]
Segment Reporting Revenue From External Customers	108		119		231		237
Technology Solutions Hardware [Member]
Segment Reporting Information [Line Items]
Segment Reporting Revenue From External Customers	21		25		42		52
Corporate [Member]
Segment Reporting Information [Line Items]
Operating profit (2) (3) (4) (5)	$ (110)		$ (97)		$ (195)		$ (103)	[5]

[1] Revenues derived from services represent less than 2% of this segment’s total revenues.

[2] Operating profit for the second quarters of 2014 and 2013 includes AWP litigation charges of $35 million and $44 million and for the first six months of 2014 and 2013 includes AWP litigation charges of $50 million and $60 million, which were recorded in operating expenses.

[3] Operating profit for the second quarter and first six months of 2014 includes last-in-first-out (“LIFO”) charges of $44 million and for the second quarter and first six months of 2013 includes LIFO charges of $3 million, which were recorded in cost of sales.

[4] Operating profit for the first six months of 2014 includes the receipt of $7 million and for the second quarter and first six months of 2013 $19 million representing our share of settlements of antitrust class action lawsuits brought against drug manufacturers, which was recorded as a reduction to cost of sales.

[5] Corporate expenses for the first six months of 2013 are net of an $81 million pre-tax gain on business combination related to the acquisition of the remaining 50% ownership interest in our corporate headquarters building.