INCOME TAXES - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
U.S. statutory rate	35.00%
Undistributed earnings of foreign subsidiaries	$ 500,000
Unrecognized tax benefits	25,100,000
Unrecognized tax benefits that would impact effective tax rate	200,000
Decrease in unrecognized tax benefits within the next twelve months	0
Unrecognized tax benefits, interest on income taxes expense	100,000
Unrecognized tax benefits, interest on income taxes accrued	100,000	100,000
Accruals for estimated penalties	0	0
Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	453,400,000
State
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	97,100,000
Canada | Foreign
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	45,000,000
Germany | Foreign
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	28,100,000
Research credit carryforward | Federal
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	2,700,000
Research credit carryforward | State
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	$ 4,000,000