Stub Period Comparative Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended										6 Months Ended		12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014
Revenues:
License and milestone fees	$ 5,076	$ 76	$ 76	$ 10,077	$ 10,692	$ 6,070	$ 5,086	$ 5,078	$ 41,417	$ 6,234	$ 5,152	$ 16,762	$ 26,915	$ 57,815	$ 39,455
Royalty revenue					195			5,099	4,625	4,166		195	195	13,867	10,346
Non-cash royalty revenue related to the sale of future royalties	6,710	6,184	5,944	7,380	6,291	5,684	5,484				12,894	11,975	25,299	5,484
Research and development support	1,427	1,354	1,335	1,059	848	772	708	532	832	776	2,781	1,620	4,014	2,848	7,187
Clinical materials revenue	633	46	53	1,198	3	2,325	1,356	718	1,426	2,027	679	2,328	3,579	5,527	2,908
Total revenues	13,846	7,660	7,408	19,714	18,029	14,851	12,611	11,427	48,300	13,203	21,506	32,880	60,002	85,541	59,896
Operating Expenses:
Research and development	33,657	32,909	38,652	36,094	38,199	35,132	30,437	25,666	27,647	28,018	66,566	73,331	148,077	111,768	106,958
General and administrative	8,536	9,459	9,298	11,235	8,054	8,329	7,261	7,000	6,872	7,095	17,995	16,383	36,916	28,228	24,469
Total operating expenses	42,494	46,498	47,950	47,329	46,253	43,461	37,698	32,666	34,519	35,113	88,992	89,714	184,993	139,996	131,427
Loss from operations	(28,648)	(38,838)	(40,542)	(27,615)	(28,224)	(28,610)	(25,087)	(21,239)	13,781	(21,910)	(67,486)	(56,834)	(124,991)	(54,455)	(71,531)
Investment income, net											259	111	325	69	44
Non-cash interest expense on liability related to the sale of future royalties and convertible senior notes	(3,647)	(5,018)	(4,956)	(4,972)	(5,059)	(5,143)	(5,437)				(8,665)	(10,202)	(20,130)	(5,437)
Interest expense on convertible senior notes	(1,099)	(1,150)									(2,249)		(138)
Other expense, net											(742)	(42)	117	(916)	123
Net loss	$ (34,152)	$ (44,731)	$ (45,922)	$ (31,928)	$ (33,227)	$ (33,740)	$ (30,474)	$ (21,618)	$ 13,635	$ (22,282)	$ (78,883)	$ (66,967)	$ (144,817)	$ (60,739)	$ (71,364)
Basic and diluted net (loss) income per common share (in dollars per share)	$ (0.39)	$ (0.51)	$ (0.53)	$ (0.37)	$ (0.38)	$ (0.39)	$ (0.35)	$ (0.25)	$ 0.16	$ (0.26)	$ (0.91)	$ (0.77)	$ (1.67)	$ (0.71)	$ (0.83)