Fair Value Measurements (Additional Information) (Detail) $ in Thousands	Sep. 30, 2015 USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contingent consideration	$ 4,705
Fair value of our revolving facility and senior debt	869,700
Carrying value of our revolving facility and senior debt	$ 851,500
4.5% Senior Notes, due December 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	4.50%
4.2% Senior Notes, due December 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	4.20%
Accrued Expenses
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contingent consideration	$ 4,700

Long-Term Debt, Carrying Value.

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Amount of liability recognized arising from contingent consideration in a business combination.

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Contractual interest rate for funds borrowed, under the debt agreement.

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