Segment Information (Details) $ in Millions	3 Months Ended				6 Months Ended
	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) segment	Sep. 30, 2016 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment					2
Revenues
Total Revenues	$ 52,061			$ 49,957	$ 103,112	$ 99,690
Operating profit
Total	239			580	872	1,552
Interest Expense	(69)			(78)	(137)	(157)
Income from Continuing Operations Before Income Taxes	178			525	636	1,437
Reversal of LIFO expense					3	(4)
Pre-tax charges recorded during period	236			0	236	0
Goodwill impairment charge	350			290	350	290
Loss from equity method investment in Change Healthcare	61			0	181	0
Total Distribution Solutions
Operating profit
Pre-tax gain recorded on sale of investment	43
Goodwill impairment charge					350
Technology Solutions
Operating profit
Goodwill impairment charge					0
Technology Solutions | Enterprise Information Solutions
Operating profit
Goodwill impairment charge				290
Operating Segments
Revenues
Total Revenues	52,061			49,957	103,112	99,690
Operating profit
Total	355			677	990	1,773
Operating Segments | Total Distribution Solutions
Revenues
Total Revenues	51,941			49,277	102,872	98,286
Operating profit
Total	$ 388			$ 851	$ 1,101	$ 1,779
Revenue derived from services, percentage (less than)	2.00%			2.00%	2.00%	2.00%
Proceeds from legal settlements						$ 142
Operating Segments | Total Distribution Solutions | LIFO Method of Accounting
Operating profit
Total	$ 29			$ 43	$ 3	(4)
Operating Segments | Total Distribution Solutions | Reportable Subsegments | North America pharmaceutical distribution and services
Revenues
Total Revenues	43,508			41,375	86,524	82,586
Operating Segments | Total Distribution Solutions | Reportable Subsegments | International pharmaceutical distribution and services
Revenues
Total Revenues	6,773			6,271	13,155	12,601
Operating Segments | Total Distribution Solutions | Reportable Subsegments | Medical-Surgical distribution and services
Revenues
Total Revenues	1,660			1,631	3,193	3,099
Operating Segments | Technology Solutions
Revenues
Total Revenues	120			680	240	1,404
Operating profit
Total	(33)			(174)	(111)	(6)
Corporate
Operating profit
Corporate Expenses, Net	(108)			$ (74)	(217)	$ (179)
Joint Venture | Change Healthcare, LLC (“Change Healthcare”)
Operating profit
Loss from equity method investment in Change Healthcare	$ 61				$ 181
Core MTS Businesses | Change Healthcare, LLC (“Change Healthcare”) | Operating Segments | Technology Solutions
Operating profit
Gain from sale of business, pre-tax		$ 37	$ 3,947