REVENUE - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Property Subject to or Available for Operating Lease [Line Items]
Operating leases	$ 6,982,111		$ 6,982,111		$ 6,914,796
Accumulated depreciation	1,438,994		1,438,994		$ 1,343,898
Assets Leased to Others | Tolling, Storage and Pipeline Transportation Services
Property Subject to or Available for Operating Lease [Line Items]
Operating leases	241,200		241,200
Accumulated depreciation	31,700		31,700
Depreciation expense	$ 900	$ 900	$ 1,800	$ 1,800