Segment Information (Revenue by Reportable Segment) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Revenue	$ 36,689	$ 39,157	$ 39,735	$ 37,341	$ 37,353	$ 35,228	$ 37,740	$ 35,213	$ 152,922	$ 145,534	$ 136,809
Non-US [Member]
Segment Reporting Information [Line Items]
Revenue									4,232	4,071	4,283
United States
Segment Reporting Information [Line Items]
Revenue									148,707	141,479	132,539
Operating Segments
Segment Reporting Information [Line Items]
Revenue									152,939	145,550	136,822
Operating Segments | Pharmaceutical
Segment Reporting Information [Line Items]
Revenue									137,495	129,917	121,241
Operating Segments | Pharmaceutical | Pharmaceutical Distribution and Specialty [Member]
Segment Reporting Information [Line Items]
Revenue									136,693	129,067
Operating Segments | Pharmaceutical | Nuclear Precision Health Services [Member]
Segment Reporting Information [Line Items]
Revenue									802	850
Operating Segments | Medical
Segment Reporting Information [Line Items]
Revenue									15,444	15,633	15,581
Operating Segments | Medical | Medical distribution and products [Member]
Segment Reporting Information [Line Items]
Revenue									13,429	13,833
Operating Segments | Medical | Cardinal Health At Home Solutions [Member]
Segment Reporting Information [Line Items]
Revenue									2,015	1,800
Corporate
Segment Reporting Information [Line Items]
Revenue									$ (17)	$ (16)	$ (13)