Goodwill - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill And Intangible Assets Disclosure [Abstract]
Impairment of goodwill	$ 17,500,000	$ 1,600,000	$ 17,532,000	$ 1,547,000	$ 0
Accumulated impairments to goodwill	$ 19,100,000	$ 1,500,000	$ 19,100,000	$ 1,500,000