Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Collaboration revenue	$ 710,487mdvn_CollaborationRevenue	$ 272,942mdvn_CollaborationRevenue	$ 181,696mdvn_CollaborationRevenue
Operating expenses:
Research and development expenses	189,570us-gaap_ResearchAndDevelopmentExpense	118,952us-gaap_ResearchAndDevelopmentExpense	95,628us-gaap_ResearchAndDevelopmentExpense
Selling, general and administrative expenses	239,071	176,231	112,282
Total operating expenses	428,641us-gaap_OperatingExpenses	295,183us-gaap_OperatingExpenses	207,910us-gaap_OperatingExpenses
Income (loss) from operations	281,846us-gaap_OperatingIncomeLoss	(22,241)us-gaap_OperatingIncomeLoss	(26,214)us-gaap_OperatingIncomeLoss
Other income (expense), net:
Interest expense	(21,690)us-gaap_InterestExpenseDebt	(20,249)us-gaap_InterestExpenseDebt	(14,985)us-gaap_InterestExpenseDebt
Interest income	46us-gaap_InvestmentIncomeInterest	193us-gaap_InvestmentIncomeInterest	229us-gaap_InvestmentIncomeInterest
Other income (expense), net	(8)us-gaap_OtherNonoperatingIncomeExpense	(201)us-gaap_OtherNonoperatingIncomeExpense	(280)us-gaap_OtherNonoperatingIncomeExpense
Total other income (expense), net	(21,652)us-gaap_NonoperatingIncomeExpense	(20,257)us-gaap_NonoperatingIncomeExpense	(15,036)us-gaap_NonoperatingIncomeExpense
Income (loss) before income tax benefit (expense)	260,194	(42,498)	(41,250)
Income tax benefit (expense)	16,258us-gaap_IncomeTaxExpenseBenefit	(115)us-gaap_IncomeTaxExpenseBenefit	(7)us-gaap_IncomeTaxExpenseBenefit
Net income (loss)	$ 276,452us-gaap_NetIncomeLoss	$ (42,613)us-gaap_NetIncomeLoss	$ (41,257)us-gaap_NetIncomeLoss
Basic net income (loss) per common share	$ 3.59us-gaap_EarningsPerShareBasic	$ (0.57)us-gaap_EarningsPerShareBasic	$ (0.56)us-gaap_EarningsPerShareBasic
Diluted net income (loss) per common share	$ 3.42us-gaap_EarningsPerShareDiluted	$ (0.57)us-gaap_EarningsPerShareDiluted	$ (0.56)us-gaap_EarningsPerShareDiluted
Weighted-average common shares used in the calculation of basic net income (loss) per common share	76,929	75,165	73,480
Weighted-average common shares used in the calculation of diluted net income (loss) per common share	85,000	75,165	73,480

Revenues earned from collaboration partners under collaboration agreements.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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