Employee Benefit Plan - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Compensation And Retirement Disclosure [Abstract]
Defined contribution plan maximum annual employer matching contribution per employee	$ 2,000	$ 500	$ 500
Employee benefit plans, contribution expense	$ 153,000	$ 59,000	$ 31,000