Goodwill and Intangibles - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill impairment	$ 0	$ 0	$ 0
Intangible asset impairment	0	0	0
Increase in gross carrying amount of intangibles	30,400,000	55,800,000
Amortization expense on intangible assets	11,259,000	6,264,000	$ 2,837,000
Intangibles on business combination	$ 30,300,000	$ 55,400,000