Long-Term Debt Debt Maturity Schedule (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Long-term Debt	$ 2,724,672	$ 2,705,718
Unamortized Debt Issuance Expense	27,699	33,017
Less amounts due in one year	(1,677)	(1,819)
Long-term Debt, Excluding Current Maturities	2,722,995	2,703,899
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	1,804
Long-term Debt, Maturities, Repayments of Principal in Year Two	672
Long-term Debt, Maturities, Repayments of Principal in Year Three	292
Long-term Debt, Maturities, Repayments of Principal in Year Four	275,740
Long-term Debt, Maturities, Repayments of Principal in Year Five	20,861
Long-term Debt, Maturities, Repayments of Principal after Year Five	2,454,043
Long-term Debt	2,753,412
Senior notes due April 2020 at 8.25%
Debt Instrument [Line Items]
Long-term Debt	74,470	74,470
Senior notes due March 2021 at 6.375%
Debt Instrument [Line Items]
Long-term Debt	20,611	20,611
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long-term Debt	201,000	185,000
Senior Secured Notes Due April 2022 Par Value [Member]
Debt Instrument [Line Items]
Long-term Debt		1,855,617
Senior Notes due April 2023 [Member]
Debt Instrument [Line Items]
Long-term Debt	494,344	493,439
Baltimore Port Facility revenue bonds in series due September 2025 at 5.75%
Debt Instrument [Line Items]
Long-term Debt	102,865	102,865
Advance royalty commitments
Debt Instrument [Line Items]
Long-term Debt	2,678	3,964
Note due through December 2012 at 6.10%
Debt Instrument [Line Items]
Long-term Debt	$ 1,672	$ 2,769

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
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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 payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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