Changes in Number of Outstanding Shares of Common Stock (Detail) - shares	6 Months Ended
	Jun. 30, 2015
Stockholders Equity Note [Abstract]
Balance at beginning of the period	17,099,882
Common stock issued	10,814,773
Restricted common stock awards granted, net of forfeitures	240,990
Common stock options exercised	202,050
Common stock issued from the exercise of Warrants	9,360
Balance at end of the period	28,367,055