- Definition

The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

+ References+ Details

Asset Acquisition and License Agreements - Additional Information (Detail) (USD $)	12 Months Ended			1 Months Ended		12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Nov. 30, 2007	Dec. 31, 2014	Dec. 31, 2011
Asset Acquisition [Line Items]
Research and development	$ 123,639,000us-gaap_ResearchAndDevelopmentExpense	$ 79,286,000us-gaap_ResearchAndDevelopmentExpense	$ 49,717,000us-gaap_ResearchAndDevelopmentExpense
Millennium
Asset Acquisition [Line Items]
License fees paid				5,000,000
Research and development				5,000,000
Millennium \| Maximum
Asset Acquisition [Line Items]
Additional license fees payable on occurrence of specified events					35,000,000
Astellas Pharma Inc
Asset Acquisition [Line Items]
License fees paid						7,200,000
Research and development						7,200,000
Percentage required to pay for any payment received under collaboration excluding royalties	20.00%				20.00%
Astellas Pharma Inc \| Maximum
Asset Acquisition [Line Items]
Additional license fees payable on occurrence of specified events					$ 71,500,000