Long Term Debt (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
Debt Instrument
Total debt	$ 1,144,247	$ 1,060,084	$ 1,085,915
Less current maturities	(7,171)	(7,182)	(106,959)
Long-term debt	1,137,076	1,052,902	978,956
6.6% Senior Notes, due 2018
Debt Instrument
Total debt	298,575	298,476	298,380
7% Debentures, Due 2025
Debt Instrument
Total debt	124,430	124,417	124,405
6.25% Senior Notes, Due 2037
Debt Instrument
Total debt	228,097	247,915	247,898
Term Loan Facility, Due 2015
Debt Instrument
Total debt	245,000	250,000	250,000
Revolving Facility
Debt Instrument
Credit Facility	145,000	35,000	60,000
AR Credit Facility
Debt Instrument
Credit Facility	100,000	100,000	100,000
Other Notes
Debt Instrument
Other notes	$ 3,145	$ 4,276	$ 5,232

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Amount borrowed under the credit facility as of the balance sheet date.

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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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Carrying amount of long-term debt, net of 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 both current and noncurrent portions, carrying amount as of the balance sheet date of other forms of debt not elsewhere specified in the taxonomy with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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