INCOME TAX - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Change in Canadian rate	$ 0	$ (3,083,000)	$ 17,000
Kemmerer deferred tax asset removal	0	(13,238,000)	0
Net valuation allowance increase	(43,600,000)
Uncertain tax positions	0	4,000,000
Penalties and interest expense	0	$ 0	$ 0
Uncertain tax positions expected to change in next 12 months	0
Federal [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	581,400,000
ICTC carryforwards	64,400,000
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 52,300,000