Nature of Business and Plan of Operations (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended								12 Months Ended
	Jul. 31, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2009
Nature of Business and Plan of Operations
Net loss		$ 22,414	$ 18,669	$ 12,753	$ 19,483	$ 16,150	$ 15,003	$ 14,233	$ 12,888	$ 73,319	$ 58,274	$ 50,912
Accumulated deficit		503,956				430,637				503,956	430,637
Cash and cash equivalents		160,938				191,206				160,938	191,206	109,156	69,639
Net proceeds from a public stock offering	$ 94,000										$ 87,980	$ 77,522