Commitments And Contingencies (Narrative) (Detail) (USD $)	12 Months Ended											12 Months Ended			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Sales Milestone Payments [Member]	Dec. 31, 2012 Sales Milestone Payments [Member] Astellas [Member]	Dec. 31, 2012 Development Milestone Payments [Member]	Dec. 31, 2012 Development Milestone Payments [Member] Astellas [Member]	Dec. 31, 2012 Letter Of Credit [Member]	Dec. 31, 2011 Letter Of Credit [Member]	Dec. 31, 2012 Collateralized Letter Of Credit [Member]	Dec. 31, 2011 Collateralized Letter Of Credit [Member]	Dec. 31, 2011 525 Market Street [Member] Y sqft	Dec. 31, 2012 525 Market Street [Member]	Sep. 30, 2012 525 Market Street [Member] sqft	Dec. 31, 2012 Oakbrook Terrace [Member] sqft	Dec. 31, 2012 201 Spear Street [Member] sqft	Dec. 31, 2012 India [Member] sqft
Commitments And Contingencies [Line Items]
Operating lease space, in square feet												57,000		29,000	15,000	14,000	9,000
Lease expiry period												June 2019			December 2019	May 2013	December 2015
Optional lease extension term, in years												5
Tenant improvement allowance												$ 3,500,000			$ 800,000
Outstanding letters of credit collateralized by restricted cash										9,200,000	6,000,000		8,000,000		800,000
Rent expense, net of sublease income	6,000,000	2,800,000	2,200,000
Restricted cash, current								300,000	500,000
Restricted cash, long-term assets	8,843,000	5,489,000						8,800,000	5,500,000
Aggregate milestone payments upon achievement of certain development and regulatory milestone events						2,800,000
Percentage of development milestone payment						10.00%	10.00%
Royalty percentage on sales						4.00%
Milestone payments eligible to earn				320,000,000		277,000,000
Percentage of sales milestone payments	10.00%	10.00%	10.00%		10.00%
Maximum eligible future sales milestone payments under collaboration arrangement					320,000,000
Coverage under its relevant insurance policies	$ 350,000