Face (par) amount of debt instrument at time of issuance.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Balance Type:	na
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- Details

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Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

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Namespace Prefix:	us-gaap_
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- Definition

Amount of statutory capital required to be maintained as of the balance sheet date under prescribed or permitted statutory accounting practices.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 505

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6486098&loc=d3e24708-158529

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Liquidity and Capital Resources) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Revolving Credit Facility [Member]	Dec. 31, 2013 Letter of Credit [Member]	Dec. 24, 2013 Letter of Credit [Member]	Mar. 31, 2014 10.75% Senior Notes [Member]	Jun. 29, 2012 10.75% Senior Notes [Member]	Feb. 04, 2011 10.75% Senior Notes [Member]	Feb. 04, 2011 10.75% Senior Notes [Member] Senior Notes Issued February 4, 2011 [Member]	Jan. 31, 2012 10.75% Senior Notes [Member] Senior Notes Issued January 31, 2012 [Member]	Dec. 31, 2013 WRMI [Member]	Dec. 31, 2013 Westmoreland Mining, LLC [Member]	Dec. 31, 2013 Westmoreland Mining, LLC [Member] Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Statutory minimum level of capital									$ 0
Senior secured note face amount							150.0	125.0
Line of credit facility, term	5 years
Stated interest rate				10.75%	10.75%	10.75%	10.75%				3.75%
Line of credit facility maximum borrowing capacity	20.0	2.0	30.0							25.0	25.0
Letters of credit outstanding amount											1.9
Line of credit facility, available borrowing capacity	$ 20.0										$ 23.1