Common Stock - Summary of Common Stock Shares Activity (Detail) - shares			3 Months Ended		9 Months Ended
	Apr. 28, 2015	May. 07, 2014	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2015
Common Stock Outstanding Roll Forward [Roll Forward]
Beginning Balance				8,512,103	8,512,103
Common stock issued through April 2015 Offering	5,376,622	6,200,000			5,376,622
Common stock issued through employee stock purchase plan			1,767	15,107	16,874
Ending Balance			13,905,599		13,905,599