INVESTMENTS IN UNCONSOLIDATED AFFILIATES (Details) $ in Thousands, bbl in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) bbl	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
INVESTMENTS IN UNCONSOLIDATED AFFILIATES
Carrying value of investments in unconsolidated affiliates	$ 243,202		$ 243,202		$ 246,700
Earnings from unconsolidated affiliates	2,960	$ 2,191	6,940	$ 9,764
Additional capital investments in unconsolidated affiliates		4,226	2,225	4,226
Cash distributions received from unconsolidated affiliates	$ 4,457	7,510	$ 12,663	15,462
BOSTCO
INVESTMENTS IN UNCONSOLIDATED AFFILIATES
Storage capacity | bbl			7.1
Percentage of ownership	42.50%		42.50%		42.50%
Carrying value of investments in unconsolidated affiliates	$ 219,646		$ 219,646		$ 223,214
Excess investment	7,300		7,300		7,400
Earnings from unconsolidated affiliates	1,885	1,670	4,794	8,244
Additional capital investments in unconsolidated affiliates		4,226	2,125	4,226
Cash distributions received from unconsolidated affiliates	3,546	6,555	10,487	13,363
Balance sheets:
Current assets	21,634		21,634		21,079
Long-term assets	488,609		488,609		500,982
Current liabilities	(10,577)		(10,577)		(15,064)
Net assets	499,666		499,666		$ 506,997
Statements of comprehensive income (loss):
Revenue	17,033	15,273	49,907	54,127
Expenses	(12,178)	(11,081)	(36,668)	(33,705)
Net earnings	$ 4,855	4,192	$ 13,239	20,422
Frontera
INVESTMENTS IN UNCONSOLIDATED AFFILIATES
Storage capacity | bbl			1.5
Percentage of ownership	50.00%		50.00%		50.00%
Carrying value of investments in unconsolidated affiliates	$ 23,556		$ 23,556		$ 23,486
Earnings from unconsolidated affiliates	1,075	521	2,146	1,520
Additional capital investments in unconsolidated affiliates			100
Cash distributions received from unconsolidated affiliates	911	955	2,176	2,099
Balance sheets:
Current assets	6,089		6,089		4,156
Long-term assets	42,505		42,505		44,194
Current liabilities	(1,482)		(1,482)		(1,376)
Net assets	47,112		47,112		$ 46,974
Statements of comprehensive income (loss):
Revenue	5,232	4,227	13,608	12,118
Expenses	(3,082)	(3,185)	(9,316)	(9,078)
Net earnings	$ 2,150	$ 1,042	$ 4,292	$ 3,040
Class A Member Ownership Interest | BOSTCO
INVESTMENTS IN UNCONSOLIDATED AFFILIATES
Cash distributions, allocation percentage			96.50%
Class B Member Ownership Interest | BOSTCO
INVESTMENTS IN UNCONSOLIDATED AFFILIATES
Cash distributions, allocation percentage			3.50%