Goodwill and Intangibles - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended	60 Months Ended
	Dec. 31, 2016	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2011
Business Acquisition [Line Items]
Goodwill	$ 52,705,000		$ 52,705,000	$ 18,851,000
Changes in the value of goodwill			0
Fully amortized intangible assets written off		$ 13,636,000
Goodwill impairment	0
2017	15,137,000		15,137,000
2018	14,792,000		14,792,000
2019	14,386,000		14,386,000
2020	14,287,000		14,287,000
2021	13,787,000		13,787,000
Acquisitions in 2016
Business Acquisition [Line Items]
Goodwill	$ 33,861,000		$ 33,861,000
Acquisitions in 2011
Business Acquisition [Line Items]
Goodwill					$ 18,851,000