Subsequent Event (Narrative) (Detail) (Subsequent Event [Member], USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended
	Jun. 30, 2012 Astellas [Member]	Jun. 30, 2012 Development Milestone Payments [Member]	Jul. 31, 2012 Equity Incentive Plan [Member]
Common stock authorized			1,800,000
Payment towards NDA triggers	$ 10.0
Share of development milestone payment		10.00%