Changes in Alliance Agreement Liability (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2007
Alliance Agreement [Line Items]
Beginning balance	$ 22,584	$ 32,487		$ 9,300
Costs related to fulfillment of technical enablement milestones	(1,917)	(9,903)	(11,000)
Ending balance	$ 20,667	$ 22,584	$ 32,487	$ 9,300