Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Goodwill And Intangible Assets Disclosure [Abstract]
Accumulated amortization expense	$ 4,300,000		$ 4,300,000		$ 3,600,000
Amortization expense	$ 473,000	$ 196,000	$ 1,200,000	$ 545,000