Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Mar. 09, 2016	Jun. 30, 2015
Document Documentand Entity Information [Abstract]
Entity Registrant Name	WESTMORELAND COAL Co
Entity Central Index Key	0000106455
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Amendment Flag	false
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 363,374,374
Entity Common Stock, Shares Outstanding		18,307,350