Debt - Carrying Value of Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt issuance costs	$ (10,521)	$ (9,372)
Total debt	685,729	743,918
Current portion of long-term debt	17,786	90,323
Less current portion of debt issuance costs	(2,964)	(4,970)
Total long-term debt	667,943	653,595
6.375% Senior Notes, due August 2020 [Member]
Debt Instrument [Line Items]
Total debt	300,000	300,000
Term Credit Facility [Member]
Debt Instrument [Line Items]
Total debt	394,250	365,290
Current portion of long-term debt	20,750	95,293
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Total debt	$ 2,000	$ 88,000