Commitments and Contingent Liabilities - Narrative (Details)	Jan. 08, 2019 municipality	Dec. 28, 2018 county	Apr. 03, 2018 state	Apr. 03, 2018 city	Dec. 30, 2017 investment_fund	Dec. 29, 2017 investment_fund	Jan. 29, 2019 case	Dec. 31, 2018 complaint case	Oct. 05, 2018 case	Sep. 17, 2018 case
Loss Contingencies [Line Items]
Complaints filed against the entity | complaint								1,400
The County of Summit, Ohio v. Purdue Pharma L.P., et al.
Loss Contingencies [Line Items]
Complaints filed against the entity									3
Cabell County Commission, West Virginia v. AmerisourceBergen Drug Corp., et al.
Loss Contingencies [Line Items]
Complaints filed against the entity								2
Boone County Commission, et al., v. Purdue Pharma L.P., et al
Loss Contingencies [Line Items]
Number of plaintiffs | county		8
In re McKesson Corporation Derivative Litigation
Loss Contingencies [Line Items]
Complaints filed against the entity										2
United States ex rel. Omni Healthcare Inc. v. McKesson Corporation, et al.
Loss Contingencies [Line Items]
Number of plaintiffs			30	2
Polygon European Equity Opportunity Master Fund et al. v. McKesson Europe Holdings GmbH & Co. KGaA,
Loss Contingencies [Line Items]
Number of plaintiffs | investment_fund						2
Davidson Kempner International (BVI) Ltd., et al. v. McKesson Europe Holdings GmbH & Co. KGaA
Loss Contingencies [Line Items]
Number of plaintiffs | investment_fund					4
Subsequent event | The County of Summit, Ohio v. Purdue Pharma L.P., et al.
Loss Contingencies [Line Items]
Complaints filed against the entity							3
Subsequent event | Boone County Commission, et al., v. Purdue Pharma L.P., et al
Loss Contingencies [Line Items]
Number of cases dismissed | municipality	21