LEASES - Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating Leases
Total right-of-use asset	$ 29,486	$ 38,562
Total lease liability	29,905	39,230
Finance Leases
Lease liability - field equipment	117
Field equipment
Operating Leases
Total right-of-use asset	27,537	35,057
Total lease liability	27,537	35,075
Finance Leases
Right-of-use asset - field equipment	219	0
Lease liability - field equipment	117	0
Corporate leases
Operating Leases
Total right-of-use asset	1,481	2,462
Total lease liability	1,900	3,129
Vehicles
Operating Leases
Total right-of-use asset	468	1,043
Total lease liability	$ 468	$ 1,026