Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in goodwill balance	$ 0		$ 0
Amortization expense of intangible assets	699,000	$ 903,000	2,100,000	$ 2,700,000
Amortization from capitalized internally developed software	$ 4,000	$ 42,000	$ 10,000	$ 136,000