Note 5 - Impairment Charges (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2016	Dec. 31, 2016
Impairment of Long-Lived Assets Held-for-use	$ 4,360	$ 37,729	$ 8,400
Property, Plant and Equipment, Net	756,138			$ 789,710
Canadian Segment [Member]
Impairment of Long-Lived Assets Held-for-use	4,360	37,729
US Segment and Other [Member]
Impairment of Long-Lived Assets Held-for-use			8,400
Open Camp Assets [Member] | Canadian Segment [Member]
Impairment of Long-Lived Assets Held-for-use	3,200
Property, Plant and Equipment, Net	0
Undeveloped Land Positions [Member] | Canadian Segment [Member]
Impairment of Long-Lived Assets Held-for-use	$ 1,200
Property, Plant and Equipment, Net		5,600
Mobile Camp Assets [Member] | Canadian Segment [Member]
Property, Plant and Equipment, Net		$ 26,600
Impaired Fixed Assets [Member] | US Segment and Other [Member]
Property, Plant and Equipment, Net			$ 3,800