Long-Term Debt - Long Term Debt Instrument (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Current portion of long-term debt	$ 45,625us-gaap_LongTermDebtCurrent	$ 100,000us-gaap_LongTermDebtCurrent
Total notes	623,471us-gaap_SeniorNotes	150,000us-gaap_SeniorNotes
Total credit agreements	529,375us-gaap_LineOfCredit	230,000us-gaap_LineOfCredit
Total long-term debt	1,152,846us-gaap_LongTermDebtNoncurrent	380,000us-gaap_LongTermDebtNoncurrent
Current portion of long-term debt	45,625us-gaap_LongTermDebtCurrent	100,000us-gaap_LongTermDebtCurrent
Total debt	1,198,471us-gaap_LongTermDebt	480,000us-gaap_LongTermDebt
Current Portion of 5-Year Term Loan Facility Expires 2019 [Member]
Debt Instrument [Line Items]
Current portion of 5-year term loan facility expires 2019	20,625
6.080% Senior Notes, Series B, Semi-Annual Interest Payments, Balloon Due 2014 [Member]
Debt Instrument [Line Items]
Current portion of senior notes		100,000
5.370% Senior Notes, Series D, Quarterly Interest Payments, Balloon Due 2015 [Member]
Debt Instrument [Line Items]
Current portion of senior notes	25,000
Total notes		25,000
5.660% Senior Notes, Series C, Semi-Annual Interest Payments, Balloon Due 2016 [Member]
Debt Instrument [Line Items]
Total notes	25,000	25,000
4.500% Senior Notes, Series E, Quarterly Interest Payments, Balloon Due 2018 [Member]
Debt Instrument [Line Items]
Total notes	100,000	100,000
4.200% Senior Notes, Semi-Annual Interest Payments, Balloon Due 2024 [Member]
Debt Instrument [Line Items]
Total notes	498,471
Periodic Payments of Interest, LIBOR Plus 1.00%, Expires December 31, 2016 [Member]
Debt Instrument [Line Items]
Total credit agreements		100,000
Quarterly Payments of Interest, LIBOR Plus 1.00%, Expires December 31, 2016 [Member]
Debt Instrument [Line Items]
Total credit agreements		100,000
Periodic Payments of Interest, LIBOR Plus 1.00%, Expires December 31, 2016 [Member]
Debt Instrument [Line Items]
Total credit agreements		30,000
5-Year Term-Loan Facility, Periodic Interest and Principal Payments, Currently LIBOR Plus 1.375%, Expires May 20, 2019
Debt Instrument [Line Items]
Total credit agreements	$ 529,375

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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- Definition

The carrying value as of the balance sheet date of the current portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt, after unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

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Carrying value as of the balance sheet date of the portion of long-term notes having the highest claim on the assets of the issuer in case of bankruptcy or liquidation, due within one year or the normal operating cycle, if longer. Senior note holders are paid off in full before any payments are made to debt holders having a lesser priority of repayment.

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