BASIS OF PRESENTATION - Business Operations (Details)	0 Months Ended	3 Months Ended	0 Months Ended
	Apr. 28, 2014 mines	Mar. 31, 2015 mines	Dec. 31, 2014
Canadian Acquisition
Business Acquisition [Line Items]
Number of mines	6	6
Westmoreland Resource Partners LP
Business Acquisition [Line Items]
Ownership percentage in partnership (percent)			79.00%
PMRU
Business Acquisition [Line Items]
Number of mines		5
Corporate Joint Venture | Canadian Acquisition
Business Acquisition [Line Items]
Ownership percentage in joint venture (percent)		50.00%
Corporate Joint Venture | PMRU
Business Acquisition [Line Items]
Ownership percentage in joint venture (percent)		50.00%