SEGMENT REPORTING - Revenue and Assets by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 27,614	$ 28,981	$ 26,989	$ 27,752	$ 28,554	$ 28,343	$ 27,871	$ 26,357	$ 111,336	$ 111,125	$ 81,763
Total assets	307,390				305,967				307,390	305,967	328,398
Continuing Operations
Segment Reporting Information [Line Items]
Total assets	307,390				305,967				307,390	305,967	328,398
Third party | Continuing Operations
Segment Reporting Information [Line Items]
Revenues									92,089	98,706	69,487
Related party | Continuing Operations
Segment Reporting Information [Line Items]
Revenues									19,247	12,419	12,276
U.S. | Continuing Operations
Segment Reporting Information [Line Items]
Total assets	229,206				224,450				229,206	224,450	250,309
U.S. | Third party | Continuing Operations
Segment Reporting Information [Line Items]
Revenues									37,336	44,792	20,134
U.S. | Related party | Continuing Operations
Segment Reporting Information [Line Items]
Revenues									5,054	5,426	6,945
Canada | Continuing Operations
Segment Reporting Information [Line Items]
Total assets	$ 78,184				$ 81,517				78,184	81,517	78,089
Canada | Third party | Continuing Operations
Segment Reporting Information [Line Items]
Revenues									54,753	53,914	49,353
Canada | Related party | Continuing Operations
Segment Reporting Information [Line Items]
Revenues									$ 14,193	$ 6,993	$ 5,331