Summary of Significant Accounting Policies (Details 2)	12 Months Ended
	Jun. 30, 2015 USD ($) item	Jun. 30, 2014 USD ($) item	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)
Inventory
Raw materials	$ 279,000	$ 437,000
Work in process	2,656,000	2,513,000
Total	2,935,000	2,950,000
Raw materials inventory write-downs	$ 1,400,000	661,000
Minimum supply period of raw materials that is not supported by firm, fixed orders and/or projections from collaborators considered to expense inventory	12 months
Rolling period of firm, fixed orders for conjugate that the company is required to manufacture	6 months
Rolling period of manufacturing projections for the quantity of conjugate the collaborator expects to need	12 months
Maximum period of firm, fixed orders and/or projections from collaborators considered for capitalizing inventory	12 months
Charges to research and development expense related to raw material inventory identified as excess	$ 1,000,000	364,000	$ 798,000
Other Accrued Liabilities
Accrued contract payments	5,830,000	2,914,000
Accrued clinical trial costs	1,735,000	1,778,000
Accrued professional services	788,000	833,000
Accrued employee benefits	567,000	454,000
Accrued public reporting charges	192,000	183,000
Other current accrued liabilities	1,329,000	506,000
Total	$ 10,441,000	6,668,000
Financial Instruments and Concentration of Credit Risk
Number of financial institutions in the U.S. in which cash and cash equivalents are primarily maintained | item	3
Number of marketable securities held by entity	$ 0
Net gains (losses) on forward contracts		$ 2,000	197,000
Number of outstanding forward contracts | item	0	0
Cash and Cash Equivalents.
Cash and cash equivalents	$ 278,109,000	$ 142,261,000	$ 194,960,000	$ 160,938,000