Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014
Quarterly Financial Information (Unaudited)
License and milestone fees	$ 76	$ 10,077	$ 10,692	$ 6,070	$ 5,086	$ 5,078	$ 41,417	$ 6,234	$ 26,915	$ 57,815	$ 39,455
Royalty revenue			195		(23)	5,099	4,625	4,166	195	13,867	10,346
Non-cash royalty revenue related to the sale of future royalties	5,944	7,380	6,291	5,684	5,484				25,299	5,484
Research and development support	1,335	1,059	848	772	708	532	832	776	4,014	2,848	7,187
Clinical materials revenue	53	1,198	3	2,325	1,356	718	1,426	2,027	3,579	5,527	2,908
Total revenues	7,408	19,714	18,029	14,851	12,611	11,427	48,300	13,203	60,002	85,541	59,896
Operating Expenses:
Research and development	38,652	36,094	38,199	35,132	30,437	25,666	27,647	28,018	148,077	111,768	106,958
General and administrative	9,298	11,235	8,054	8,329	7,261	7,000	6,872	7,095	36,916	28,228	24,469
Total operating expenses	47,950	47,329	46,253	43,461	37,698	32,666	34,519	35,113	184,993	139,996	131,427
(Loss) income from operations	(40,542)	(27,615)	(28,224)	(28,610)	(25,087)	(21,239)	13,781	(21,910)	(124,991)	(54,455)	(71,531)
Non-cash interest expense on liability related to the sale of future royalties and convertible senior notes	(4,956)	(4,972)	(5,059)	(5,143)	(5,437)				(20,130)	(5,437)
Other (expense) income, net	(424)	659	56	13	50	(379)	(146)	(372)
Net (loss) income	$ (45,922)	$ (31,928)	$ (33,227)	$ (33,740)	$ (30,474)	$ (21,618)	$ 13,635	$ (22,282)	$ (144,817)	$ (60,739)	$ (71,364)
Basic and diluted net (loss) income per common share (in dollars per share)	$ (0.53)	$ (0.37)	$ (0.38)	$ (0.39)	$ (0.35)	$ (0.25)	$ 0.16	$ (0.26)	$ (1.67)	$ (0.71)	$ (0.83)