UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Gathering services and related fees	$ 84,361	$ 118,013
Natural gas, NGLs and condensate sales	26,117	11,120
Other revenues	6,842	6,672
Total revenues	117,320	135,805
Costs and expenses:
Cost of natural gas and NGLs	20,286	9,052
Operation and maintenance	24,604	23,692
General and administrative	14,385	14,132
Depreciation and amortization	26,677	28,569
Transaction costs	57	0
(Gain) loss on asset sales, net	(74)	3
Long-lived asset impairment	0	284
Total costs and expenses	85,935	75,732
Other (expense) income	(7)	71
Interest expense	(15,122)	(16,716)
Early extinguishment of debt	0	(22,020)
Deferred Purchase Price Obligation	(21,658)	(20,883)
(Loss) income before income taxes and income (loss) from equity method investees	(5,402)	525
Income tax benefit (expense)	171	(452)
Income (loss) from equity method investees	1,386	(656)
Net loss	(3,845)	(583)
Net income attributable to noncontrolling interest	85	102
Net loss attributable to SMLP	(3,930)	(685)
Less net income attributable to General Partner, including IDRs	2,058	2,092
Net income (loss) attributable to limited partners	(5,988)	(2,777)
Series A Preferred Units
Costs and expenses:
Net income (loss) attributable to limited partners	7,125	0
Common units
Costs and expenses:
Net income (loss) attributable to limited partners	$ (13,113)	$ (2,777)
Loss per limited partner unit:
Basic (in dollars per share)	$ (0.18)	$ (0.04)
Diluted (in dollars per share)	$ (0.18)	$ (0.04)
Weighted-average limited partner units outstanding:
Basic (shares)	73,134	72,149
Diluted (shares)	73,134	72,149