Segment Information (Details) $ in Millions	3 Months Ended
	Jun. 30, 2016 USD ($) segment	Jun. 30, 2015 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment	2
Revenues
Total Revenues	$ 49,733	$ 47,546
Operating profit
Total	972	931
Interest Expense	(79)	(89)
Income from Continuing Operations Before Income Taxes	912	855
Gain on disposition of business	(113)	51
Operating Segments
Revenues
Total Revenues	49,733	47,546
Operating profit
Total	1,096	1,068
Operating Segments | Total Distribution Solutions
Revenues
Total Revenues	49,009	46,810
Operating profit
Total	$ 928	$ 910
Revenue derived from services, percentage (less than)	2.00%	2.00%
Proceeds from legal settlements	$ 142	$ 59
Operating Segments | Total Distribution Solutions | LIFO Method of Accounting
Operating profit
Total	47	91
Operating Segments | Total Distribution Solutions | Reportable Subsegments | North America pharmaceutical distribution and services
Revenues
Total Revenues	41,211	39,532
Operating Segments | Total Distribution Solutions | Reportable Subsegments | International pharmaceutical distribution and services
Revenues
Total Revenues	6,330	5,838
Operating Segments | Total Distribution Solutions | Reportable Subsegments | Medical-Surgical distribution and services
Revenues
Total Revenues	1,468	1,440
Operating Segments | Technology Solutions
Revenues
Total Revenues	724	736
Operating profit
Total	168	158
Operating Segments | Technology Solutions | Nurse Triage
Operating profit
Gain on disposition of business		51
Corporate
Operating profit
Corporate Expenses, Net	(105)	(124)
Segment Reconciling Items
Operating profit
Interest Expense	$ (79)	$ (89)