Note 5 - Liabilities Related to Sale of Future Royalties - Deferred Revenue Activity (Details) - Royalty Arrangement [Member] - HealthCare Royalty Partners III, L.P. [Member] $ in Millions	6 Months Ended
Dec. 31, 2017 USD ($)
Total Liability related to sale of future royalties, June 30, 2017	$ 16.7
Non-cash royalty revenue paid to HCRP	(0.3)
Non-cash interest expense recognized	0.8
Total Liability related to sale of future royalties, December 31, 2017	$ 17.2

Amount of deferred revenue as of balance sheet date. Deferred revenue represents collections of cash or other assets related to a revenue producing activity for which revenue has not yet been recognized. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.3)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.4(a).Q1)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Name:	us-gaap_DeferredRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant