Commitments and Contingent Liabilities (Details) - Litigation, Government Subpoenas and Investigations				9 Months Ended
	Jan. 19, 2018 defendant	Jan. 11, 2018 complaint	Jan. 05, 2018 complaint	Dec. 31, 2017 complaint case
Loss Contingencies [Line Items]
Number of complaints				192
Number of remaining cases | case				29
Subsequent Event | The Cherokee Nation v. McKesson Corporation, et al.
Loss Contingencies [Line Items]
Other defendants named | defendant	5
Subsequent Event | In re McKesson Corporation Derivative Litigation
Loss Contingencies [Line Items]
Number of suits filed			2
Subsequent Event | In re McKesson Corporation Stockholder Derivative Litigation
Loss Contingencies [Line Items]
Number of complaints		2
Number of remaining cases		3