Note 7 - Differences Between the Company's Effective Tax Rate and the Statutory Tax Rate (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income tax benefit at federal statutory rate (35%)	$ (15,057,000)	$ (15,816,000)	$ (10,538,000)
State and local income taxes net of federal tax benefit	(819,000)	(1,286,000)	(839,000)
Permanent items	560,000	258,000	738,000
Rate change	1,012,000	22,000	1,892,000
Expiration of attribute carryforwards	330,000	373,000	242,000
Research and development tax credits	(10,454,000)	$ (748,000)	$ (1,206,000)
Orphan drug credit	4,307,000
Other	(218,000)	$ (115,000)	$ 1,144,000
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	$ 20,339,000	$ 17,312,000	$ 8,567,000
Income tax expense