Commitments And Contingencies (Narrative) (Detail) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2012
Coverage under its relevant insurance policies		$ 350,000
Sales Milestone Payments [Member] | Astellas [Member]
Percentage of share as per ARN-509		10.00%
Eligible to receive milestone payments	320,000,000	320,000,000
Minimum [Member]
Lease expiry period		July 2012
Maximum [Member]
Lease expiry period		May 2013
525 Market Street [Member]
Operating lease space, in square feet	57,000	57,000
Lease expiry period		June 2019
Optional lease extension term, in years		5
Tenant improvement allowance		2,400,000
Outstanding letters of credit collateralized by restricted cash	5,100,000	5,100,000
Lease term, in years		7
Oakbrook Terrace [Member]
Operating lease space, in square feet	15,000	15,000
Lease expiry period		December 2019
Tenant improvement allowance		800,000
Outstanding letters of credit collateralized by restricted cash	$ 800,000	$ 800,000
201 Spear Street [Member]
Operating lease space, in square feet	34,000	34,000
India [Member]
Operating lease space, in square feet	9,000	9,000
Lease expiry period		December 2015.