Commitments and Contingencies (Details) (USD $)	12 Months Ended			1 Months Ended					12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2010	Apr. 30, 2012 830 Winter Street, Waltham, MA sqft	Dec. 31, 2009 830 Winter Street, Waltham, MA sqft	Jul. 31, 2007 830 Winter Street, Waltham, MA item	Jul. 27, 2007 830 Winter Street, Waltham, MA sqft	Jul. 27, 2007 830 Winter Street, Waltham, MA Maximum	Jun. 30, 2012 Norwood, MA
Operating leases
Area of laboratory and office space leased (in square feet)				7,310			89,000
Initial lease term period				3 years		12 years
Number of additional terms for which lease agreement can be extended						2
Additional term period for which lease agreement can be extended						5 years			5 years
Area of property covered under sublease agreement (in square feet)					14,100
Additional period for which sublease agreement can be extended					2 years
Construction allowance received								$ 13,300,000
Leasehold improvements recorded under construction allowance							12,000,000
Receipts from the landlord towards leasehold improvements						10,800,000
Facilities rent expense, net of sublease income	4,800,000	4,600,000	5,400,000
Minimum rental commitments under the non-cancelable operating lease agreements
2013	6,375,000
2014	6,463,000
2015	6,581,000
2016	6,353,000
2017	6,420,000
Thereafter	16,556,000
Total minimum lease payments	48,748,000
Total minimum rental income from subleases	(1,749,000)
Total minimum lease payments, net	46,999,000
Collaborations
Maximum amount payable in the future under collaborative agreements	$ 43,000,000