INCOME TAXES - Reconciliation of Income Tax Expense Computed at the Federal Statutory Rate to the Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
(Loss) income before income taxes and equity method investments	$ (9,422)	$ 40,423
Federal income tax (benefit) provision at statutory rate	(1,978)	14,147
Loss passed through to common unitholders	5,794	10,385
Income tax provision (benefit) at federal statutory income tax rate, including income passed through to common unitholders	3,816	24,532
State income taxes, net of federal effect	1,705	5,344
Change in valuation allowance	6,317	(48,598)
Foreign tax rate differences	(59)	(1,202)
Uncertain tax positions	150	124
Deferred tax rate change due to newly-enacted U.S. tax law	0	69,992
Permanent differences and other	630	1,107
Income tax provision	$ 12,559	$ 51,299