SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Effect on Partners' Capital (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital	$ 69,464	$ 84,890	$ 58,526
General Partner
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital	3,275	180	356	$ 438
Common units | Limited Partner
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital	107,903	136,645	128,903	146,645
Class A units | Limited Partner
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital			1,929
Subordinated units | Limited Partner
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital	(39,723)	(55,237)	(70,936)	(88,151)
Accumulated other comprehensive income (loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital	$ (3,009)	$ 1,834	(1,726)	$ (1,004)
As reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital			46,818
As reported | General Partner
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital			111
As reported | Common units | Limited Partner
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital			122,802
As reported | Class A units | Limited Partner
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital			1,811
As reported | Subordinated units | Limited Partner
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital			(76,749)
As reported | Accumulated other comprehensive income (loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital			(1,157)
Adjustments | Topic 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital			11,708
Adjustments | Topic 606 | General Partner
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital			245
Adjustments | Topic 606 | Common units | Limited Partner
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital			6,101
Adjustments | Topic 606 | Class A units | Limited Partner
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital			118
Adjustments | Topic 606 | Subordinated units | Limited Partner
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital			5,813
Adjustments | Topic 606 | Accumulated other comprehensive income (loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital			$ (569)