Debt - Carrying Value of Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Total debt	$ 784,406	$ 891,935
Less current portion of term credit facility	95,293	87,352
Total long-term debt	689,113	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	$ 484,406	547,935
Revolving Credit Facility
Debt Instrument [Line Items]
Total debt		$ 44,000