Fair Value Measurements (Level 3 Contingent Purchase Price) (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Ending balance	$ 140,712,000mdco_ContingentPurchasePrice	$ 302,363,000mdco_ContingentPurchasePrice
Transfers from Level 1 to Level 2	0
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Ending balance	351,134,000	302,363,000
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	302,363,000	18,971,000
Fair value adjustment to contingent purchase price included in net income (loss)	10,871,000	16,942,000
Ending balance	351,134,000	302,363,000
Incline Therapeutics, Inc. [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of contingent purchase price	0	87,200,000
ProFibrix [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of contingent purchase price	0	82,550,000
Rempex [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of contingent purchase price	0	96,700,000
Tenaxis Medical [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of contingent purchase price	$ 37,900,000	$ 0

Noncurrent portion of the fair value, as of the balance sheet date, of potential payments under the contingent consideration arrangements.

No definition available.

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- Definition

Amount of increase (decrease) in the value of right to a contingent consideration asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 50

-Paragraph 4

-Subparagraph (a)(1)

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- Definition

Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

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- Definition

Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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