BASIS OF PRESENTATION (Details) (USD $)	1 Months Ended	3 Months Ended	6 Months Ended						3 Months Ended		6 Months Ended
	May 30, 2013	Jun. 30, 2013	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Senior secured notes	Dec. 31, 2012 Senior secured notes	Jun. 30, 2013 Westmoreland Mining LLC (WML) Senior secured notes	Jun. 30, 2013 Westmoreland Coal Company Senior secured notes	Jun. 30, 2013 Other operating income	Jun. 30, 2012 Other operating income	Jun. 30, 2013 Other operating income	Jun. 30, 2012 Other operating income
Debt Instrument [Line Items]
Debt and Capital Lease Obligations		$ 349,036,000	$ 349,036,000	$ 360,989,000	$ 251,500,000	$ 252,000,000	$ 94,500,000	$ 251,500,000
Percentage membership interest sold to third party	99.00%
Increase in other operating income and net income attributable to noncontrolling interest		3,700,000	3,700,000
Business interruption insurance proceeds recorded in income									$ 6,500,000	$ 5,500,000	$ 11,300,000	$ 8,600,000