SUPPLEMENTAL CASH FLOW INFORMATION - Schedule of supplemental cash flow information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Supplemental cash flow information:
Cash interest paid	$ 62,441	$ 66,435
Less capitalized interest	2,268	5,752
Interest paid (net of capitalized interest)	60,173	60,683
Cash paid for taxes		150
Noncash investing and financing activities:
Capital expenditures in trade accounts payable (period-end accruals)	10,233	22,166
Warrant issuance for GP Buy-In Transaction	2,300
Asset contribution to an equity method investment		23,643
ASC Topic 842
Noncash investing and financing activities:
Right-of-use assets relating to ASC Topic 842	2,964	$ 5,448
Series A Preferred Units
Noncash investing and financing activities:
Accretion of Subsidiary Series A Preferred Units	$ 5,856