QUARTERLY FINANCIAL DATA (UNAUDITED) Table (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Data [Abstract]
Net income	$ 5,999	$ 17,320	$ 15,073	$ 16,676	$ 12,959	$ 16,917	$ 15,527	$ 26,805	$ 55,068	$ 72,208	$ 61,427
Basic net income per unit	$ 0.14	$ 0.40	$ 0.35	$ 0.39	$ 0.30	$ 0.39	$ 0.37	$ 0.62	$ 1.28	$ 1.68	$ 1.44
Diluted net income per unit	0.14	0.40	0.35	0.39	0.30	0.39	0.37	0.62	1.28	1.68	$ 1.44
Cash distributions per unit applicable to limited partners	$ 0.545	$ 0.545	$ 0.545	$ 0.545	$ 0.545	$ 0.545	$ 0.545	$ 0.545	$ 2.18	$ 2.18