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Description of the maturity date of the debt instrument including whether the debt matures serially and, if so, a brief description of the serial maturities.

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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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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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Long-Term Debt (Schedule of Long-Term Debt) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Debt Instrument [Line Items]
Total debt	$ 551,372us-gaap_LongTermDebt	$ 566,152us-gaap_LongTermDebt
Current maturities	(28,144)us-gaap_LongTermDebtCurrent	(20,376)us-gaap_LongTermDebtCurrent
Long-term debt, less current maturities	523,228us-gaap_LongTermDebtNoncurrent	545,776us-gaap_LongTermDebtNoncurrent
Unamortized debt discount	(20,920)	(26,516)
Term Loan Maturing June 2018 [Member]
Debt Instrument [Line Items]
Total debt	277,500	292,500
Current maturities	(22,500)
Long-term debt, less current maturities	255,000
Maturity date	June 2018
Convertible Senior Notes 2032 [Member]
Debt Instrument [Line Items]
Total debt	200,000	200,000
Long-term debt, less current maturities	179,080
Unamortized debt discount	(20,920)	(26,500)	(35,400)
Maturity date	March 2032
Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Long-term debt, less current maturities				275,000
MARAD Debt [Member]
Debt Instrument [Line Items]
Total debt	94,792	100,168
Current maturities	(5,644)
Long-term debt, less current maturities	$ 89,148
Maturity date	February 2027