ACQUISITIONS (Narrative) (Details) - USD ($)				3 Months Ended		9 Months Ended
		Apr. 03, 2017	Feb. 28, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Net revenue				$ 222,380,000	$ 186,232,000	$ 628,567,000	$ 518,273,000
Net income (loss)	[1]			7,947,000	$ 2,070,000	10,724,000	$ (12,933,000)
Nowait, Inc
Business Acquisition [Line Items]
Equity interest in acquiree, percentage			20.00%
Total purchase consideration			$ 39,837,000
Held in escrow account			$ 7,945,000
Escrow deposit duration			2 years
Acquisition-related transaction costs				0		100,000
Net revenue				1,300,000		2,600,000
Net income (loss)				(1,900,000)		(5,100,000)
Turnstyle Analytics Inc
Business Acquisition [Line Items]
Total purchase consideration		$ 19,741,000
Held in escrow account		$ 3,093,000
Escrow deposit duration		18 months
Acquisition-related transaction costs				0		300,000
Net revenue				400,000		800,000
Net income (loss)				$ (4,000,000)		$ (4,600,000)
Purchase consideration including acquisition compensation cost		$ 21,000,000
Acquisition compensation cost		$ 1,000,000

[1] The structure of the Company’s common stock changed during the year ended December 31, 2016. Refer to Note 13 for details.