Tons Of Coal

No definition available.

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- Definition

The value of all consideration given or received by the Entity in the significant acquisition or disposal.

+ References

No definition available.

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- Definition

The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid in more than four and within five years from the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 47

-Paragraph 7

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 440

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308

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- Definition

The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid within one year of the balance sheet date.

+ References

+ Details

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- Definition

The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid in more than three and within four years from the balance sheet date.

+ References

+ Details

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- Definition

The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid in more than one and within two years from the balance sheet date.

+ References

+ Details

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- Definition

The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation to be paid in more than two and within three years from the balance sheet date.

+ References

+ Details

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Property Transactions (Details) (USD $) In Millions, unless otherwise specified	Mar. 18, 2010 Montana Otter Creek [Member]	Nov. 12, 2009 Great Northern Properties Limited Partnership [Member]	Dec. 14, 2011 South Hilight [Member]	Dec. 31, 2011 Reserves [Member] Montana Otter Creek [Member]	Dec. 31, 2011 Reserves [Member] South Hilight [Member]	Dec. 31, 2011 Capital Additions [Member]
Property, Plant and Equipment [Line Items]
Mining operations purchase price	$ 85.8	$ 73.1	$ 300.0
Coal reserve in tons				1,400,000,000	222,000,000
Unrecorded Unconditional Purchase Obligation Due Current						23.4
Unrecorded Unconditional Purchase Obligation Due in Two Years						83.4
Unrecorded Unconditional Purchase Obligation Due in Three Years						67.3
Unrecorded Unconditional Purchase Obligation Due in Four Years						60.0
Unrecorded Unconditional Purchase Obligation Due in Five Years						$ 60.0