Long-Term Debt - Summary of Long-Term Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Total long-term debt	$ 389,115	$ 404,612
Less current portion	(7,580)	(5,734)
Long-term debt, net of current portion	381,535	398,878
Total long-term debt	389,115	404,612
Revolving Credit Facility, Due Mar. 2020 [Member]
Debt Instrument [Line Items]
Total long-term debt	83,464
Total long-term debt	83,464
Revolving Credit Facility, Due Nov. 2016 [Member]
Debt Instrument [Line Items]
Total long-term debt		90,555
Total long-term debt		90,555
5.375% Notes, Due Oct. 2020 [Member]
Debt Instrument [Line Items]
Total long-term debt	250,000	250,000
Long-term debt, net of current portion	250,000	250,000
Total long-term debt	250,000	250,000
2.40% Term Loan, Due Jun. 2022 [Member]
Debt Instrument [Line Items]
Total long-term debt	10,803	12,155
Total long-term debt	10,803	12,155
2.05% Term Loan, Due Mar. 2023 [Member]
Debt Instrument [Line Items]
Total long-term debt	44,848	51,902
Total long-term debt	$ 44,848	$ 51,902