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Contingencies and Environmental Liabilities - Propecia/Proscar Litigation - Narrative (Details)	12 Months Ended
	Dec. 31, 2017 legalmatter Plaintiff
Propecia
Loss Contingencies [Line Items]
Loss contingency, pending claims number	775
Propecia | Cases alleging cancer
Loss Contingencies [Line Items]
Number of plaintiff groups | Plaintiff	20
Propecia/Proscar | Other State Court | California
Loss Contingencies [Line Items]
Loss contingency, pending claims number	1
Propecia/Proscar | Other State Court | Ohio
Loss Contingencies [Line Items]
Loss contingency, pending claims number	1
Propecia/Proscar | Other State Court | MASSACHUSETTS
Loss Contingencies [Line Items]
Loss contingency, pending claims number	1

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Number of plaintiffs that have filed claims pertaining to a loss contingency.

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Number of pending claims pertaining to a loss contingency.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349

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