Earnings Per Share Attributable to Cardinal Health, Inc. (Reconciliation of Common Shares Used to Compute Basic and Diluted EPS) (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Weighted-average common shares–basic (in shares)	294	292	293	294
Effect of dilutive securities:
Employee stock options, restricted share units, and performance share units (in shares)	1	2	2	0
Weighted-average common shares–diluted (in shares)	295	294	295	294