Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	May 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 312,441,000	$ 304,805,000	$ 286,249,000
Goodwill impairment	0
Indefinite-lived intangible asset impairment	0
Amortization of intangible assets	6,849,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2019	25,000,000
2020	25,000,000
2021	25,000,000
2022	22,200,000
2023	$ 20,200,000