Class of Warrant or Right, Strike Price of Warrants or Rights

No definition available.

Name:	mdco_ClassOfWarrantOrRightStrikePriceOfWarrantsOrRights
Namespace Prefix:	mdco_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Shares Exercisable Upon Conversion

+ References

No definition available.

+ Details

Name:	mdco_SharesExercisableUponConversion
Namespace Prefix:	mdco_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentRepurchasedFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The aggregate amount paid by the entity to reacquire the right to purchase equity shares at a predetermined price, usually issued together with corporate debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3291-108585

+ Details

Name:	us-gaap_PaymentsForRepurchaseOfWarrants
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash inflow associated with the amount received from holders exercising their stock warrants.

+ References

No definition available.

+ Details

Name:	us-gaap_ProceedsFromWarrantExercises
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=mdco_A2017WarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mdco_ConvertibleSeniorNotesDue2017Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Convertible Senior Notes (Warrants) (Details) - USD ($) $ / shares in Units, shares in Millions	1 Months Ended	9 Months Ended
	Jun. 30, 2012	Sep. 30, 2016	Sep. 30, 2015	Jun. 30, 2016
Debt Instrument [Line Items]
Settlement of warrants		$ 87,874,000	$ 0
2017 Warrants [Member]
Debt Instrument [Line Items]
Proceeds from sale of warrants	$ 38,400,000
Settlement of warrants		$ 87,900,000
Shares exercisable upon conversion	2
Exercise price of warrants (in dollars per share)	$ 34.20
Senior Notes [Member] \| Convertible Senior Notes Due 2017 [Member]
Debt Instrument [Line Items]
Debt, aggregate principal amount repurchased				$ 220,000,000