Significant Accounting Policies - Certain Cash and Non-Cash Transactions (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Interest paid	$ 10,000	$ 10,996	$ 13,525
Income taxes paid, net	19,836	19,105	$ 1,870
Accounts payable for capital expenditures	$ 621	$ 2,516