Interim Financial Statements (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Dec. 31, 2010
PRO 140 [Abstract]
Proceeds From License Fees Received PRO 140	$ 3,500,000
Eligible to receive [Abstract]
Percentage Of Royalties		5.00%	5.00%
Maximum License Fee Receivable On Commencement Of US Or Ex US Phase 3 Trial Of PRO 140		1,500,000	1,500,000
Maximum License Fee Receivable Upon US Or EU Marketing Approval Of PRO 140		5,000,000	5,000,000
Relistor [Abstract]
Number of countries approved sale of Relistor		50	50
Receipt of upfront ex-U.S. sublicensee revenue					200,000
Eligible to receive
License fee receivable on U.S. Marketing approval for subcutaneous Relistor, maximum		40,000,000	40,000,000
License fee receivable on U.S. Marketing approval for oral formulation of Relistor, maximum		50,000,000	50,000,000
Payment receivable on achievement of specified U.S. sales targets		200,000,000	200,000,000
Percentage of royalties, minimum (in hundredths)		15.00%	15.00%
Percentage of royalties, maximum (in hundredths)		19.00%	19.00%
Percentage of upfront, milestone, reimbursement or other revenue (in hundredths)		60.00%	60.00%
Annual U.S. sales, minimum			100,000,000
Funding and Financial Matters [Abstract]
Cash and cash equivalents at end of period		41,096,000	41,096,000	77,998,000	70,105,000	47,918,000
Decrease in cash and cash equivalents		6,700,000	29,009,000	(30,080,000)
Minimum number of years cash will fund operations (in years)			1 year
Authorized amount of common shares under stock repurchase program, maximum			15,000,000
Remaining authorized amount of common shares under stock repurchase program			12,300,000
Stock repurchased during the period, value		$ 0	$ 0