OPERATING SEGMENTS AND GEOGRAPHIC INFORMATION - Summary of Revenues by Country (Details) - USD ($) $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 71,650	$ 72,960	$ 73,022	$ 73,873	$ 77,155	$ 82,928	$ 82,253	$ 73,822	$ 146,668	$ 156,075	$ 219,628	$ 239,003	$ 291,505	$ 316,158	$ 280,718
United States
Segment Reporting Information [Line Items]
Revenues													232,735	251,444	220,018
Canada
Segment Reporting Information [Line Items]
Revenues													33,089	37,956	38,750
Other countries
Segment Reporting Information [Line Items]
Revenues													$ 25,681	$ 26,758	$ 21,950