Consolidated Statements Of Stockholders' Equity (USD $) In Thousands, except Share data		Total	Common Stock [Member]		Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Balances at Dec. 31, 2009	[1]	$ 25,274	$ 676		$ 202,023	$ (12)	$ (177,413)
Balance, Shares at Dec. 31, 2009	[1]		67,646,124
Common stock issued under Medivation Equity Incentive Plan, net of shares withheld for employee taxes, Amount	[1]	2,625	15		2,610
Common stock issued under Medivation Equity Incentive Plan, net of shares withheld for employee taxes, Shares	[1]		1,501,534
Stock-based compensation expense		13,530			13,530
Excess tax benefit from employee stock plan awards		278			278
Change in comprehensive income		14				14
Net loss		(34,037)					(34,037)
Balances at Dec. 31, 2010	[1]	7,684	691		218,441	2	(211,450)
Balance, Shares at Dec. 31, 2010	[1]		69,147,658
Common stock issued under Medivation Equity Incentive Plan, net of shares withheld for employee taxes, Amount	[1]	15,734	23		15,711
Common stock issued under Medivation Equity Incentive Plan, net of shares withheld for employee taxes, Shares	[1]		2,316,018
Stock-based compensation expense		13,774			13,774
Change in comprehensive income		11				11
Net loss		(38,841)					(38,841)
Net proceeds from stockholder securities law settlement		2,959			2,959
Balances at Dec. 31, 2011	[1]	1,321	714		250,885	13	(250,291)
Balance, Shares at Dec. 31, 2011		71,463,676	71,463,676	[1]
Common stock issued under Medivation Equity Incentive Plan, net of shares withheld for employee taxes, Amount	[1]	20,438	34		20,404
Common stock issued under Medivation Equity Incentive Plan, net of shares withheld for employee taxes, Shares	[1]		3,311,263
Stock-based compensation expense		23,678			23,678
Change in comprehensive income		20				20
Net loss		(41,257)					(41,257)
Equity component of Convertible Notes, net of issuance costs		69,335			69,335
Stock appreciation rights- reclassification from current liabilities to stockholders' equity		110			110
Balances at Dec. 31, 2012	[1]	$ 73,645	$ 748		$ 364,412	$ 33	$ (291,548)
Balance, Shares at Dec. 31, 2012		74,774,939	74,774,939	[1]

[1] All share, par, and additional paid-in capital amounts have been retroactively adjusted to reflect the Company's September 21, 2012 two-for-one forward stock split. This stock split resulted in the issuance of approximately 37.0 million shares of the Company's common stock.