BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)	12 Months Ended
	Dec. 31, 2015 USD ($) customer	Dec. 31, 2014 USD ($) customer	Dec. 31, 2013 USD ($)
Accounting Policies [Line Items]
Estimated period of amortization for the cost of inventory evaluation tools	5 years
Amortization expense	$ 100,000	$ 400,000	$ 1,500,000
Depreciation expense	2,800,000	2,200,000	2,200,000
Impairment charge related to property and equipment	$ 0	0	0
General length of product warranty	12 months
Expected dividend yield	0.00%
Stock-based compensation expense	$ 2,280,000	1,526,000	1,433,000
Net foreign currency transaction loss	(300,000)		$ (600,000)
Net foreign currency transaction gain		300,000
Cumulative translation adjustment	$ 16,300,000	$ 18,200,000
Minimum
Accounting Policies [Line Items]
Estimated useful lives of assets	3 years
Maximum
Accounting Policies [Line Items]
Estimated useful lives of assets	7 years
Customer concentration risk | Accounts receivable
Accounting Policies [Line Items]
Number of major customers | customer	5	1
Net accounts receivable, major customer A | Customer concentration risk | Accounts receivable
Accounting Policies [Line Items]
Percentage of net accounts receivable	36.00%	74.00%
Net accounts receivable, major customer B | Customer concentration risk | Accounts receivable
Accounting Policies [Line Items]
Percentage of net accounts receivable	12.00%
Net accounts receivable, major customer C | Customer concentration risk | Accounts receivable
Accounting Policies [Line Items]
Percentage of net accounts receivable	12.00%
Net accounts receivable, major customer D | Customer concentration risk | Accounts receivable
Accounting Policies [Line Items]
Percentage of net accounts receivable	11.00%
Net accounts receivable, major customer E | Customer concentration risk | Accounts receivable
Accounting Policies [Line Items]
Percentage of net accounts receivable	10.00%
Equipment sales
Accounting Policies [Line Items]
Percent revenue recognized upon shipment	90.00%
Percent cost recognized upon shipment	100.00%
Percent revenue recognized upon customer acceptance	10.00%
Installation services
Accounting Policies [Line Items]
Percentage of total invoice amount typically assigned to the installation element in customer agreements	10.00%