Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net loss	$ (41,257)	$ (38,841)	$ (34,037)
Adjustments for non-cash operating items:
Amortization of deferred revenue	(100,944)	(60,389)	(62,508)
Stock-based compensation	23,678	13,885	13,530
Amortization of debt discount and debt issuance costs	9,663
Depreciation and amortization	1,614	430	465
Loss on disposal of equipment	80
Accretion of discount on securities	(166)	(65)	(281)
Changes in operating assets and liabilities:
Receivables from collaboration partners	(22,913)	8,643	(14,698)
Prepaid expenses and other current assets	(1,114)	(1,945)	(224)
Other non-current assets	(581)	166	(322)
Accounts payable	(3,750)	2,341	(1,611)
Accrued expenses and other current liabilities	23,062	(2,555)	13,738
Interest payable	1,698
Deferred revenue		3,000	10,000
Other non-current liabilities	8,210	(785)	884
Net cash used in operating activities	(102,720)	(76,115)	(75,064)
Cash flows from investing activities:
Purchases of short-term investments	(424,757)	(74,956)	(209,888)
Maturities of short-term investments	275,000	100,075	331,000
Purchases of property and equipment	(13,972)	(132)	(197)
Change in restricted cash	(3,197)	(5,146)	1,500
Net cash (used in) provided by investing activities	(166,926)	19,841	122,415
Cash flows from financing activities:
Proceeds from issuance of Convertible Notes, net	250,987
Financing transaction costs	(614)
Proceeds from issuance of common stock under Medivation Equity Incentive Plan	22,046	15,734	2,625
Tax withholdings related to net share settlements of performance share awards	(1,608)
Net proceeds from stockholder securities law settlement		2,959
Excess tax benefits from stock-based compensation			278
Net cash provided by financing activities	270,811	18,693	2,903
Net increase (decrease) in cash and cash equivalents	1,165	(37,581)	50,254
Cash and cash equivalents at beginning of year	70,136	107,717	57,463
Cash and cash equivalents at end of year	71,301	70,136	107,717
Supplemental disclosures of cash flow information:
Interest	3,623
Income taxes	23	5,358
Non-cash investing and financing activities:
Stock appreciation rights-reclassification from current liabilities to stockholders' equity	110
Property and equipment expenditures incurred but not yet paid	$ 254	$ 154