INCOME TAXES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
U.S. statutory rate	35.00%	35.00%	35.00%
Undistributed earnings of foreign subsidiaries	$ 400,000
Unrecognized tax benefits	24,300,000
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	0	$ 100,000	$ 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	447,900,000
State
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	113,000,000
Canada | Foreign
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	38,000,000
Germany | Foreign
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	29,200,000
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