Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended										1 Months Ended		12 Months Ended	40 Months Ended	1 Months Ended	12 Months Ended			31 Months Ended	1 Months Ended		31 Months Ended	12 Months Ended	1 Months Ended	36 Months Ended		12 Months Ended	1 Months Ended				12 Months Ended	1 Months Ended		12 Months Ended	132 Months Ended	1 Months Ended		21 Months Ended	1 Months Ended
	Jun. 30, 2014 item	Jun. 30, 2014 Development and Commercialization License item	Jun. 30, 2013 Development and Commercialization License	Jun. 30, 2012 Development and Commercialization License	Jun. 30, 2014 Development and Commercialization License Minimum	Jun. 30, 2014 Development and Commercialization License Maximum	Jun. 30, 2014 Development and Commercialization License Roche's Kadcyla Minimum	Jun. 30, 2014 Development and Commercialization License Roche's Kadcyla Maximum	Jun. 30, 2014 Right-to-Test Agreements Minimum	Jun. 30, 2014 Right-to-Test Agreements Maximum	Dec. 31, 2004 Janssen Exclusive license Maytansinoid agent	Jul. 31, 2014 Janssen Exclusive license Maytansinoid agent Subsequent event	Jun. 30, 2014 Amgen Development and Commercialization License Exclusive license item	Dec. 31, 2012 Amgen Development and Commercialization License Exclusive license item	May 31, 2013 Amgen Development and Commercialization License Non-exclusive license item	Jun. 30, 2014 Amgen Oxford BioTherapeutics Ltd Exclusive license item	Jun. 30, 2014 Bayer HealthCare Development and Commercialization License Exclusive license item	Jun. 30, 2014 Biotest Development and Commercialization License Exclusive license item	Jun. 30, 2014 Lilly	Dec. 31, 2013 Lilly Development and Commercialization License	Dec. 31, 2011 Lilly Development and Commercialization License item	Jun. 30, 2014 Lilly Development and Commercialization License	Jun. 30, 2014 Lilly Development and Commercialization License Exclusive license item	Dec. 31, 2011 Lilly Right-to-Test Agreements	Oct. 31, 2013 Novartis	Oct. 31, 2013 Novartis Development and Commercialization License	Jun. 30, 2014 Novartis Development and Commercialization License Exclusive license item	Nov. 30, 2013 Novartis Right-to-Test Agreements	Oct. 31, 2013 Novartis Right-to-Test Agreements	Mar. 31, 2013 Novartis Right-to-Test Agreements	Oct. 31, 2010 Novartis Right-to-Test Agreements	Jun. 30, 2014 Roche Development and Commercialization License Exclusive license item	May 31, 2005 Roche Development and Commercialization License Exclusive license Roche's Kadcyla	Jul. 31, 2003 Sanofi Development and Commercialization License Exclusive license item	Jun. 30, 2014 Sanofi Development and Commercialization License Exclusive license item	Jun. 30, 2014 Sanofi Development and Commercialization License Exclusive license	Aug. 31, 2008 Sanofi Right-to-Test Agreements	Dec. 31, 2006 Sanofi Right-to-Test Agreements	Aug. 31, 2008 Sanofi Right-to-Test Agreements	Jul. 31, 2014 Phase IIb clinical trial SAR650984 Sanofi Development and Commercialization License Exclusive license Subsequent event
Summary of Significant Accounting Policies
Portion of upfront payment recognized												$ 241,000
Payments received under collaboration agreement											1,000,000								28,200,000	2,000,000		23,500,000		20,000,000	60,200,000	55,000,000		1,000,000	1,000,000	1,000,000	45,000,000		2,000,000			16,500,000	3,500,000	500,000	4,000,000	3,000,000
Number of types of licensing and development agreements with collaborative partners	2
Number of single-target licenses													4	3	1	1	1	1			2		1				2					5			1
Number of licenses to multiple individual targets																																			1
Number of licenses to two related targets																											1
Number of related targets																											2							1
Period after product launch in which the company will earn royalty payments					10 years	12 years	10 years	12 years
Average involvement period over which the upfront payments on single-target licenses are amortized		6 years 6 months
Difference between the full cost to manufacture and amounts received from collaborators for preclinical and clinical materials		$ 2,300,000	$ 755,000	$ 85,000
Number of types of milestone payments under collaborative arrangements		3
Average period over which upfront payments are deferred and recognized									12 months	18 months
Number of quarters in arrear for revenue recognition		1