EQUITY AND MEZZANINE EQUITY - Series D Preferred Units (Details) - $ / shares	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Temporary Equity [Line Items]
Partnership units, converted (in shares)	1.37931
Conversion price (in dollars per share)	$ 72.50
Series D Preferred Units
Temporary Equity [Line Items]
Preferred units, shares issued (in shares)	165,600	0
Preferred units, par value (in dollars per share)	$ 100	$ 100
Distribution rate	3.862%