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Long-Term Debt - Summary of Long-Term Debt (Detail) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016
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Debt Instrument [Line Items] |  |
Total long-term debt | $ 483,330 | $ 375,161
Less current portion | (11,298) | (8,961)
Unamortized deferred issuance costs | (1,934) | (2,553)
Long-term debt, net of current portion | 470,098 | 363,647
Revolving Credit Facility, Due Mar. 2020 [Member] |  |
Debt Instrument [Line Items] |  |
Total long-term debt | 171,200 | 61,595
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
2.40% Term Loan, Due Jun. 2022 [Member] |  |
Debt Instrument [Line Items] |  |
Total long-term debt | 7,710 | 8,282
2.05% Term Loan, Due Mar. 2023 [Member] |  |
Debt Instrument [Line Items] |  |
Total long-term debt | 33,607 | 35,163
1.30% Term Loan, Due Jun. 2023 [Member] |  |
Debt Instrument [Line Items] |  |
Total long-term debt | 9,423 | 9,788
1.55% Term Loan, Due Sep. 2025 [Member] |  |
Debt Instrument [Line Items] |  |
Total long-term debt | $ 11,390 | $ 10,333

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