Subsequent Event - Additional Information (Detail) $ / shares in Units, $ in Thousands		2 Months Ended	3 Months Ended		6 Months Ended
	Jul. 31, 2015 $ / shares	Jun. 30, 2015 USD ($) $ / shares	Sep. 30, 2015 USD ($) shares	Jun. 30, 2015 USD ($) $ / shares shares	Jun. 30, 2015 USD ($) $ / shares	Jun. 30, 2014 USD ($)	Dec. 31, 2014 $ / shares
Subsequent Event [Line Items]
Convertible Notes, aggregate principal amount		$ 167,800		$ 167,800	$ 167,800
Repayment of convertible notes in cash					90,994	$ 1
Non-cash loss on extinguishment of Convertible Notes				$ (7,868)	$ (7,871)
Common stock, par value | $ / shares		$ 0.01		$ 0.01	$ 0.01		$ 0.01
Common Stock [Member]
Subsequent Event [Line Items]
Common stock split, description					On July 31, 2015, the Company announced that its Board of Directors has declared a two-for-one stock split of Medivation's common stock to be effected through a stock dividend. Shareholders of record as of August 13, 2015, will receive one additional share of Medivation common stock, par value $0.01, for each share they hold as of the record date. The share distribution is scheduled for September 15, 2015.
Common stock split, record date					Aug. 13, 2015
Subsequent Event [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Stock split of common stock	2
Common stock, par value | $ / shares	$ 0.01
Convertible Senior Notes Due 2017 [Member] | Senior Notes [Member]
Subsequent Event [Line Items]
Repayment of convertible notes in cash		$ 90,300		$ 1,900
Common stock, shares issued on redemption of convertible notes | shares				1,049,679
Non-cash loss on extinguishment of Convertible Notes				$ 7,900	$ 7,900
Scenario, Forecast [Member]
Subsequent Event [Line Items]
Convertible Notes, aggregate principal amount			$ 167,800
Repayment of convertible notes in cash			$ 167,800
Common stock, shares issued on redemption of convertible notes | shares			1,769,609
Scenario, Forecast [Member] | Convertible Senior Notes Due 2017 [Member] | Senior Notes [Member]
Subsequent Event [Line Items]
Convertible Notes, aggregate principal amount			$ 167,800
Repayment of convertible notes in cash			$ 167,800
Common stock, shares issued on redemption of convertible notes | shares			1,769,609
Non-cash loss on extinguishment of Convertible Notes			$ 13,000