Revenue from Collaboration Agreement (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenue from Collaboration Agreement
Bayer's obligation to pay royalties to the Company for sales of Nexavar	$ 0		$ 0
Revenue from collaboration agreement
Revenue from collaboration agreement	81,828	72,704	152,135	144,736
Nexavar | More than
Revenue from Collaboration Agreement
Number of countries in which product is marketed and sold	100		100
Bayer
Revenue from collaboration agreement
Onyx's share of collaboration commercial profit	77,126	65,913	143,318	132,605
Reimbursement of Onyx's shared marketing expenses	4,702	6,791	8,817	12,131
Revenue from collaboration agreement	$ 81,828	$ 72,704	$ 152,135	$ 144,736