Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal, through the balance sheet date and due to be paid within one year (or one operating cycle, if longer) of the balance sheet date.

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Carrying value as of the balance sheet date of [accrued] interest payable on all forms of debt, including trade payables, that has been incurred and is unpaid. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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- Definition

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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Long-Term Debt (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2010
Debt Instrument [Line Items]
Capital Lease Obligations, Current	$ 8,789		$ 8,941
Debt	3,128,804	3,129,017
Less amounts due in one year	(4,564)	(4,544)
Long-Term Debt	3,124,240	3,124,473
Accrued interest	113,586			63,363
Senior Notes Due April 2017 at 8.00%
Debt Instrument [Line Items]
Debt	1,500,000	1,500,000
Senior notes due April 2020 at 8.25%
Debt Instrument [Line Items]
Debt	1,250,000	1,250,000
Senior notes due March 2021 at 6.375%
Debt Instrument [Line Items]
Debt	250,000	250,000
Baltimore Port Facility revenue bonds in series due September 2025 at 5.75%
Debt Instrument [Line Items]
Debt	102,865	102,865
Advance royalty commitments
Debt Instrument [Line Items]
Debt	20,394	20,394
Other long-term notes maturing at various dates through 2031
Debt Instrument [Line Items]
Debt	$ 5,545	$ 5,758