Long-Term Debt (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Long-Term Debt
Debt Instrument, Unamortized Discount (Premium), Net	$ 82,329	$ 63,813
Total long-term debt	3,373,752	3,386,052
Less current portion	(29,016)	(95,015)
Long-term debt, net of current portion	3,344,736	3,291,037
Six Point Two Five Percent Senior Notes Due Twenty Twenty One [Member]
Long-Term Debt
Carrying amount of debt	700,000	700,000
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Six Point Zero Zero Percent Senior Notes Due Twenty Nineteen [Member]
Long-Term Debt
Carrying amount of debt	800,000	800,000
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Nine Point Seven Five Percent Senior Notes Due Twenty Eighteen [Member]
Long-Term Debt
Carrying amount of debt	500,000	500,000
Debt Instrument, Unamortized Discount (Premium), Net	3,786	4,839
Debt Instrument, Interest Rate, Stated Percentage	9.75%
anr_TermLoanDueTwentyTwenty [Member]
Long-Term Debt
Carrying amount of debt	621,875	0
Debt Instrument, Unamortized Discount (Premium), Net	2,964
Term Loan Due Twenty Sixteen [Member]
Long-Term Debt
Carrying amount of debt	0	540,000
Debt Instrument, Unamortized Discount (Premium), Net		519
anr_ThreePointSevenFivePercentConvertibleSeniorNotesDueTwentySeventeenMember [Domain]
Long-Term Debt
Debt Instrument, Unamortized Discount (Premium), Net	57,663
Total long-term debt	287,337
Three Point Two Five Percent Convertible Senior Notes [Member]
Long-Term Debt
Debt Instrument, Unamortized Discount (Premium), Net	8,332	20,261
Two Point Three Seven Five Percent Convertible Senior Notes Due Twenty Fifteen [Member]
Long-Term Debt
Debt Instrument, Unamortized Discount (Premium), Net	9,584	38,194
Other
Long-Term Debt
Carrying amount of debt	81,234	86,203
Convertible Debt [Member] \| Six Point Two Five Percent Senior Notes Due Twenty Twenty One [Member]
Long-Term Debt
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Convertible Debt [Member] \| Six Point Zero Zero Percent Senior Notes Due Twenty Nineteen [Member]
Long-Term Debt
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Convertible Debt [Member] \| Nine Point Seven Five Percent Senior Notes Due Twenty Eighteen [Member]
Long-Term Debt
Debt Instrument, Interest Rate, Stated Percentage	9.75%
Convertible Debt [Member] \| anr_ThreePointSevenFivePercentConvertibleSeniorNotesDueTwentySeventeenMember [Domain]
Long-Term Debt
Carrying amount of debt	345,000	0
Debt Instrument, Interest Rate, Stated Percentage	3.75%
Convertible Debt [Member] \| Three Point Two Five Percent Convertible Senior Notes [Member]
Long-Term Debt
Carrying amount of debt	305,275	536,162
Debt Instrument, Interest Rate, Stated Percentage	3.25%
Convertible Debt [Member] \| Two Point Three Seven Five Percent Convertible Senior Notes Due Twenty Fifteen [Member]
Long-Term Debt
Carrying amount of debt	$ 102,697	$ 287,500
Debt Instrument, Interest Rate, Stated Percentage	2.375%

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

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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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Contractual interest rate for funds borrowed, under the debt agreement.

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

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Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

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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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