Fair Value Measurements - Schedule of Liabilities Measured at Fair Value (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fair Value Disclosures [Abstract]
Current maturities on long-term debt	$ 51,330	$ 21,330
Long-term debt	1,798,620	1,802,644
Carrying value of long-term obligation		1,823,974
Fair value of long-term obligation		1,862,091
Derivative financial instruments	$ 1,548

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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Derivative instrument obligations meeting the definition of a liability which the Company is a party to 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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