Condensed Consolidating Guarantor Financial Statements - Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues:
Sales Revenue, Goods, Net	$ 368,006	$ 210,126	$ 741,367	$ 447,022
Sales Revenue, Services, Net	88,487	62,200	156,680	126,273
Other	16,596	15,051	31,142	28,933
Revenue, Net	473,089	287,377	929,189	602,228
Expenses:
Costs of products sold, exclusive of depreciation and amortization shown below	340,107	176,842	689,105	373,789
Operating	73,346	54,707	125,429	104,899
General and administrative	26,752	20,775	48,396	41,835
Depreciation and amortization	25,602	25,055	50,201	49,106
Loss (gain) on disposal or impairment, net	(234)	1,685	2,176	14,992
Total expenses	465,573	279,064	915,307	584,621
Earnings from equity method investments	17,753	17,078	34,844	40,149
Loss on issuance of common units by equity method investee	0	0	0	(41)
Operating income	25,269	25,391	48,726	57,715
Other expenses (income), net:
Interest Expense	13,477	18,011	27,344	35,588
Loss on early extinguishment of debt	8	0	19,930	0
Foreign currency transaction loss (gain)	(1,011)	1,543	(1,011)	3,012
Loss (gain) on sale or impairment of equity method investment	0	(9,120)	0	30,644
Other expense (income), net	(441)	(490)	(591)	(678)
Total other expenses, net	12,033	9,944	45,672	68,566
Income (loss) from continuing operations before income taxes	13,236	15,447	3,054	(10,851)
Income tax expense (benefit)	3,625	4,658	3,720	(16,749)
Income (loss) from continuing operations	9,611	10,789	(666)	5,898
Income from discontinued operations, net of income taxes	0	(2)	0	(4)
Net income (loss)	9,611	10,787	(666)	5,894
Less: net income attributable to noncontrolling interests	0	1,922	0	10,942
Net income (loss) attributable to SemGroup	9,611	8,865	(666)	(5,048)
Other comprehensive income (loss), net of income taxes	(8,952)	(6,591)	(14,985)	(2,482)
Comprehensive income (loss)	18,563	17,378	14,319	8,376
Less: comprehensive income attributable to noncontrolling interests	0	1,922	0	10,942
Comprehensive income (loss) attributable to SemGroup	18,563	15,456	14,319	(2,566)
Consolidation, Eliminations [Member]
Revenues:
Sales Revenue, Goods, Net	0	0	0	0
Sales Revenue, Services, Net	0	0	0	0
Other	0	0	0	0
Revenue, Net	0	0	0	0
Expenses:
Costs of products sold, exclusive of depreciation and amortization shown below	0	0	0	0
Operating	0	0	0	0
General and administrative	0	0	0	0
Depreciation and amortization	0	0	0	0
Loss (gain) on disposal or impairment, net	0	0	0	0
Total expenses	0	0	0	0
Earnings from equity method investments	(26,420)	(7,887)	(47,086)	(14,495)
Loss on issuance of common units by equity method investee				0
Operating income	(26,420)	(7,887)	(47,086)	(14,495)
Other expenses (income), net:
Interest Expense	(207)	(236)	(396)	(473)
Loss on early extinguishment of debt	0		0
Foreign currency transaction loss (gain)	0	0	0	0
Loss (gain) on sale or impairment of equity method investment		0		0
Other expense (income), net	207	236	396	473
Total other expenses, net	0	0	0	0
Income (loss) from continuing operations before income taxes	(26,420)	(7,887)	(47,086)	(14,495)
Income tax expense (benefit)	0	0	0	0
Income (loss) from continuing operations		(7,887)		(14,495)
Income from discontinued operations, net of income taxes		0		0
Net income (loss)	(26,420)	(7,887)	(47,086)	(14,495)
Less: net income attributable to noncontrolling interests		0		0
Net income (loss) attributable to SemGroup		(7,887)		(14,495)
Other comprehensive income (loss), net of income taxes	0	0	0	0
Comprehensive income (loss)	(26,420)	(7,887)	(47,086)	(14,495)
Less: comprehensive income attributable to noncontrolling interests		0		0
Comprehensive income (loss) attributable to SemGroup		(7,887)		(14,495)
Reportable Legal Entities [Member] | Parent Company [Member]
Revenues:
Sales Revenue, Goods, Net	0	0	0	0
Sales Revenue, Services, Net	0	0	0	0
Other	0	0	0	0
Revenue, Net	0	0	0	0
Expenses:
Costs of products sold, exclusive of depreciation and amortization shown below	0	0	0	0
Operating	0	0	0	0
General and administrative	10,613	4,782	16,543	10,654
Depreciation and amortization	530	393	1,003	773
Loss (gain) on disposal or impairment, net	0	0	0	0
Total expenses	11,143	5,175	17,546	11,427
Earnings from equity method investments	25,104	6,854	44,295	13,960
Loss on issuance of common units by equity method investee				(41)
Operating income	13,961	1,679	26,749	2,492
Other expenses (income), net:
Interest Expense	4,725	(1,496)	10,591	(2,911)
Loss on early extinguishment of debt	8		19,930
Foreign currency transaction loss (gain)	0	0	0	0
Loss (gain) on sale or impairment of equity method investment		(9,120)		30,644
Other expense (income), net	(247)	(249)	(440)	(487)
Total other expenses, net	4,486	(10,865)	30,081	27,246
Income (loss) from continuing operations before income taxes	9,475	12,544	(3,332)	(24,754)
Income tax expense (benefit)	(136)	3,679	(2,666)	(19,706)
Income (loss) from continuing operations		8,865		(5,048)
Income from discontinued operations, net of income taxes		0		0
Net income (loss)	9,611	8,865	(666)	(5,048)
Less: net income attributable to noncontrolling interests		0		0
Net income (loss) attributable to SemGroup		8,865		(5,048)
Other comprehensive income (loss), net of income taxes	5,369	(18,480)	8,950	1,986
Comprehensive income (loss)	4,242	27,345	(9,616)	(7,034)
Less: comprehensive income attributable to noncontrolling interests		0		0
Comprehensive income (loss) attributable to SemGroup		27,345		(7,034)
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Revenues:
Sales Revenue, Goods, Net	333,371	180,529	674,159	387,803
Sales Revenue, Services, Net	37,549	36,815	75,599	77,012
Other	0	0	0	0
Revenue, Net	370,920	217,344	749,758	464,815
Expenses:
Costs of products sold, exclusive of depreciation and amortization shown below	310,506	153,413	632,163	326,667
Operating	28,014	28,918	56,134	58,018
General and administrative	8,443	7,806	15,373	14,954
Depreciation and amortization	17,667	17,388	34,497	34,159
Loss (gain) on disposal or impairment, net	(18)	1,713	1,964	15,059
Total expenses	364,612	209,238	740,131	448,857
Earnings from equity method investments	19,069	18,111	37,635	40,684
Loss on issuance of common units by equity method investee				0
Operating income	25,377	26,217	47,262	56,642
Other expenses (income), net:
Interest Expense	9,598	20,767	18,418	41,207
Loss on early extinguishment of debt	0		0
Foreign currency transaction loss (gain)	0	0	0	0
Loss (gain) on sale or impairment of equity method investment		0		0
Other expense (income), net	(3)	0	(5)	0
Total other expenses, net	9,595	20,767	18,413	41,207
Income (loss) from continuing operations before income taxes	15,782	5,450	28,849	15,435
Income tax expense (benefit)	0	0	0	0
Income (loss) from continuing operations		5,450		15,435
Income from discontinued operations, net of income taxes		(1)		(3)
Net income (loss)	15,782	5,449	28,849	15,432
Less: net income attributable to noncontrolling interests		1,922		10,942
Net income (loss) attributable to SemGroup		3,527		4,490
Other comprehensive income (loss), net of income taxes	256	(485)	330	(701)
Comprehensive income (loss)	15,526	5,934	28,519	16,133
Less: comprehensive income attributable to noncontrolling interests		1,922		10,942
Comprehensive income (loss) attributable to SemGroup		4,012		5,191
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Revenues:
Sales Revenue, Goods, Net	34,635	29,597	67,208	59,219
Sales Revenue, Services, Net	50,938	25,385	81,081	49,261
Other	16,596	15,051	31,142	28,933
Revenue, Net	102,169	70,033	179,431	137,413
Expenses:
Costs of products sold, exclusive of depreciation and amortization shown below	29,601	23,429	56,942	47,122
Operating	45,332	25,789	69,295	46,881
General and administrative	7,696	8,187	16,480	16,227
Depreciation and amortization	7,405	7,274	14,701	14,174
Loss (gain) on disposal or impairment, net	(216)	(28)	212	(67)
Total expenses	89,818	64,651	157,630	124,337
Earnings from equity method investments	0	0	0	0
Loss on issuance of common units by equity method investee				0
Operating income	12,351	5,382	21,801	13,076
Other expenses (income), net:
Interest Expense	(639)	(1,024)	(1,269)	(2,235)
Loss on early extinguishment of debt	0		0
Foreign currency transaction loss (gain)	(1,011)	1,543	(1,011)	3,012
Loss (gain) on sale or impairment of equity method investment		0		0
Other expense (income), net	(398)	(477)	(542)	(664)
Total other expenses, net	(2,048)	42	(2,822)	113
Income (loss) from continuing operations before income taxes	14,399	5,340	24,623	12,963
Income tax expense (benefit)	3,761	979	6,386	2,957
Income (loss) from continuing operations		4,361		10,006
Income from discontinued operations, net of income taxes		(1)		(1)
Net income (loss)	10,638	4,360	18,237	10,005
Less: net income attributable to noncontrolling interests		0		0
Net income (loss) attributable to SemGroup		4,360		10,005
Other comprehensive income (loss), net of income taxes	(14,577)	12,374	(24,265)	(3,767)
Comprehensive income (loss)	$ 25,215	(8,014)	$ 42,502	13,772
Less: comprehensive income attributable to noncontrolling interests		0		0
Comprehensive income (loss) attributable to SemGroup		$ (8,014)		$ 13,772