BUSINESS, PRESENTATION, AND RECENT ACCOUNTING PRONOUNCEMENTS - Geographic Information - Revenue (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Number of segments | segment			1
Revenue Recognition	$ 52,979	$ 51,337	$ 151,223	$ 158,581
Property and equipment, net	40,444		40,444		$ 40,551
United States [Member]
Revenue Recognition	52,094	50,026	146,602	153,088
Property and equipment, net	26,560		26,560		26,708
Canada [Member]
Revenue Recognition	885	$ 1,311	4,621	$ 5,493
Property and equipment, net	$ 13,884		$ 13,884		$ 13,843