Debt - Carrying Value of Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Total debt	$ 938,583	$ 891,935
Less current portion of term credit facility	95,293	87,352
Total long-term debt	843,290	804,583
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	460,583	547,935
Revolving Credit Facility
Debt Instrument [Line Items]
Total debt	$ 178,000	$ 44,000