Consolidated statements of operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenue:
External customers	$ 39,328	$ 27,143	$ 115,570	$ 79,196
Affiliates	1,310	10,126	6,830	33,004
Total revenue	40,638	37,269	122,400	112,200
Operating costs and expenses and other:
Direct operating costs and expenses	(17,048)	(16,655)	(50,657)	(47,481)
Direct general and administrative expenses	(764)	(1,117)	(2,925)	(2,810)
Allocated general and administrative expenses	(2,841)	(2,835)	(8,524)	(8,440)
Allocated insurance expense	(969)	(944)	(2,776)	(2,812)
Reimbursement of bonus awards expense	(251)	(121)	(2,144)	(1,185)
Depreciation and amortization	(8,169)	(7,711)	(24,168)	(22,524)
Earnings from unconsolidated affiliates	2,960	2,191	6,940	9,764
Total operating costs and expenses and other	(27,082)	(27,192)	(84,254)	(75,488)
Operating income	13,556	10,077	38,146	36,712
Other expenses:
Interest expense	(1,467)	(2,198)	(6,627)	(6,083)
Amortization of deferred financing costs	(204)	(167)	(614)	(607)
Total other expenses	(1,671)	(2,365)	(7,241)	(6,690)
Net earnings	11,885	7,712	30,905	30,022
Less-earnings allocable to general partner interest including incentive distribution rights	(2,429)	(1,803)	(6,727)	(5,546)
Net earnings allocable to limited partners	$ 9,456	$ 5,909	$ 24,178	$ 24,476
Net earnings per limited partner unit-basic (in dollars per unit)	$ 0.58	$ 0.37	$ 1.49	$ 1.52
Net earnings per limited partner unit-diluted (in dollars per unit)	$ 0.58	$ 0.37	$ 1.49	$ 1.52