Fair Value Measurements (Detail) - USD ($)		1 Months Ended	3 Months Ended
	Jan. 29, 2015	Jan. 31, 2015	Mar. 31, 2016	Mar. 31, 2015	Oct. 31, 2012
Fair Value Disclosures [Abstract]
Debt Instrument, Face Amount					$ 5,400,000.0
Number of convertible note payable converted in to common stock (in shares)	1,356,738
Conversion price per share (in dollars per share)	$ 4.00
Stock price at date of conversion (in dollars per share)	$ 18.58
Gain (loss) in estimated fair value of convertible note payable		$ (1,800,000)	$ 0	$ (1,811,000)