Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net loss	$ (42,613)	$ (41,257)	$ (38,841)
Adjustments for non-cash operating items:
Amortization of deferred revenue	(25,396)	(100,944)	(60,389)
Stock-based compensation	37,078	23,678	13,885
Amortization of debt discount and debt issuance costs	13,456	9,663
Depreciation on property and equipment	3,449	1,614	430
Accretion of discount on securities	(168)	(166)	(65)
Loss on disposal of equipment	158	80
Changes in operating assets and liabilities:
Receivables from collaboration partners	(71,752)	(22,913)	8,643
Prepaid expenses and other current assets	(3,953)	(1,114)	(1,945)
Other non-current assets	(7,353)	(581)	166
Accounts payable, accrued expenses and other current liabilities	27,889	19,312	(214)
Interest payable		1,698
Deferred revenue			3,000
Other non-current liabilities	996	8,210	(785)
Net cash used in operating activities	(68,209)	(102,720)	(76,115)
Cash flows from investing activities:
Purchases of short-term investments	(144,926)	(424,757)	(74,956)
Maturities of short-term investments	370,000	275,000	100,075
Purchases of property and equipment	(7,535)	(13,972)	(132)
Change in restricted cash	(713)	(3,197)	(5,146)
Net cash provided by (used in) investing activities	216,826	(166,926)	19,841
Cash flows from financing activities:
Proceeds from issuance of common stock under Medivation Equity Incentive Plan	8,870	22,046	15,734
Proceeds from issuance of Convertible Notes, net		250,987
Financing transaction costs		(614)
Tax withholdings related to net share settlement of performance share awards		(1,608)
Net proceeds from stockholder securities law settlement			2,959
Net cash provided by financing activities	8,870	270,811	18,693
Net increase (decrease) in cash and cash equivalents	157,487	1,165	(37,581)
Cash and cash equivalents at beginning of year	71,301	70,136	107,717
Cash and cash equivalents at end of year	228,788	71,301	70,136
Supplemental disclosures of cash flow information:
Interest	6,792	3,623
Income taxes, net of refunds	(127)	23	5,358
Non-cash investing and financing activities:
Property and equipment expenditures incurred but not yet paid	99	254	154
Stock appreciation rights-reclassification from current liabilities to stockholders' equity		$ 110