Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense of intangible assets	$ 25,855	$ 16,549
Estimated Future Amortization Expense by Fiscal Year [Abstract]
2018	24,000
2019	22,400
2020	17,300
2021	14,500
2022	9,800
After 2022	$ 28,500