INCOME TAXES - Summary of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred income tax assets:
Net operating loss carryforwards	$ 99,481	$ 93,704
Property and equipment	35,535	38,556
Goodwill and intangible assets	9,253	0
Deferred revenue	1,439	971
Non-deductible interest	23,181	10,028
Leases - ASC 842	20,811	0
Stock-based compensation	2,073	1,486
Provision for doubtful accounts	682	956
Accrued compensation	308	1,008
Tax credits carried forward	1,832	2,735
Other	1,919	1,785
Total deferred income tax assets	196,514	151,229
Deferred income tax liabilities:
Leases - ASC 842	(15,889)	0
Contracts assets	(6,244)	(6,186)
Goodwill and intangible assets	0	(375)
Refinancing costs	(416)	(4,130)
Total deferred income tax liabilities	22,549	10,691
Net deferred income tax assets	173,965	140,538
Valuation allowance	(173,841)	(142,749)	$ (132,712)	$ (164,865)
Net deferred income tax assets (liabilities)	$ 124
Net deferred income tax assets (liabilities)		$ (2,211)