Components of Long Term Debt (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Long-term Debt	$ 450,250	$ 65,000
Less: unamortized discount	(30,020)	0
Less: current portion	3,381	0
LONG-TERM DEBT	416,849	65,000
Convertible Senior Notes
Debt Instrument [Line Items]
Principal amount of convertible notes outstanding	150,000	0
Term Loan Credit Facility
Debt Instrument [Line Items]
Principal amount of convertible notes outstanding	297,750	0
Revolver
Debt Instrument [Line Items]
Principal amount of convertible notes outstanding	0	65,000
Industrial Revenue Bond
Debt Instrument [Line Items]
Principal amount of convertible notes outstanding	$ 2,500	$ 0

The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount.

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The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

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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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