SHAREHOLDERS' EQUITY AND PARTNERS' CAPITAL (At-The-Market Equity Program) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Mar. 01, 2013
Class of Stock [Line Items]
Common stock offering, maximum aggregate price				$ 300,000,000
Commission to sales agent, percent				2.00%
Issuance of shares of stock (in shares)	335,417	278,093	246,168
Common stock offering, maximum remaining aggregate price	$ 88,507,000
Common Stock
Class of Stock [Line Items]
Issuance of shares of stock (in shares)	8,419,298
Net proceeds	$ 209,596,000
At The Market Stock Sales
Class of Stock [Line Items]
Issuance of shares of stock (in shares)	211,493,000
Proceeds from sale of common stock weighted average price per share	$ 25.12