Condensed Consolidating Guarantor Financial Statements - Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Condensed Income Statements, Captions [Line Items]
Other Nonoperating Income (Expense)	$ 491	$ 95	$ 678	$ 186
Revenues:
Product	210,126	288,736	447,022	508,867
Service	62,200	66,604	126,273	128,481
Other	15,051	21,886	28,933	38,188
Revenue	287,377	377,226	602,228	675,536
Expenses:
Cost of products sold	176,842	244,158	373,789	436,230
Operating	54,707	60,800	104,899	113,890
General and administrative	20,775	22,917	41,835	55,227
Depreciation and amortization	25,048	24,674	49,095	48,408
Loss on disposal or impairment of long-lived assets, net	(1,685)	(1,372)		(2,430)
Loss (gain) on disposal or impairment, net	(1,685)	(1,372)	(14,992)	(2,430)
Total expenses	279,057	353,921	584,610	656,185
Earnings from equity method investments	17,078	23,903	40,149	44,462
Gain (loss) on issuance of common units by equity method investee	0	5,897	(41)	5,897
Operating income	25,398	53,105	57,726	69,710
Other expenses (income), net:
Interest expense	18,875	16,822	37,810	31,413
Foreign currency transaction loss (gain)	1,543	(295)	3,012	(814)
Total other expenses, net	10,807	9,809	70,788	15,896
Loss (gain) on sale or impairment of equity method investment	(9,120)	(6,623)	30,644	(14,517)
Income (loss) from continuing operations before income taxes	14,591	43,296	(13,062)	53,814
Income tax expense (benefit)	4,658	14,861	(16,749)	19,603
Income (loss) from continuing operations	9,933	28,435	3,687	34,211
Loss from discontinued operations, net of income taxes	(2)	(2)	(4)	(2)
Net income	9,931	28,433	3,683	34,209
Less: net income attributable to noncontrolling interests	1,922	5,136	10,942	9,446
Net income (loss) attributable to SemGroup	8,009	23,297	(7,259)	24,763
Other comprehensive income (loss), net of income taxes	6,591	5,520	2,482	(3,540)
Comprehensive income (loss)	16,522	33,953	6,165	30,669
Less: comprehensive income attributable to noncontrolling interests	1,922	5,136	10,942	9,446
Comprehensive income (loss) attributable to SemGroup	14,600	28,817	(4,777)	21,223
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Other Nonoperating Income (Expense)	249	778	487	1,570
Revenues:
Product	0	0	0	0
Service	0	0	0	0
Other	0	0	0	0
Revenue	0	0	0	0
Expenses:
Cost of products sold	0	0	0	0
Operating	0	0	0	0
General and administrative	4,782	4,626	10,654	22,228
Depreciation and amortization	393	329	773	623
Loss on disposal or impairment of long-lived assets, net	0	0		0
Loss (gain) on disposal or impairment, net			0
Total expenses	5,175	4,955	11,427	22,851
Earnings from equity method investments	6,557	28,583	13,147	43,388
Gain (loss) on issuance of common units by equity method investee		5,897	(41)	5,897
Operating income	1,382	29,525	1,679	26,434
Other expenses (income), net:
Interest expense	(936)	781	(1,513)	2,203
Foreign currency transaction loss (gain)	0	(5)	0	(5)
Total other expenses, net	(10,305)	(6,625)	28,644	(13,889)
Loss (gain) on sale or impairment of equity method investment	(9,120)	(6,623)	30,644	(14,517)
Income (loss) from continuing operations before income taxes	11,687	36,150	(26,965)	40,323
Income tax expense (benefit)	3,679	12,853	(19,706)	15,560
Income (loss) from continuing operations	8,008	23,297	(7,259)	24,763
Loss from discontinued operations, net of income taxes	0	0	0	0
Net income	8,008	23,297	(7,259)	24,763
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to SemGroup	8,008	23,297	(7,259)	24,763
Other comprehensive income (loss), net of income taxes	18,480	(2,346)	(1,986)	6,300
Comprehensive income (loss)	26,488	20,951	(9,245)	31,063
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to SemGroup	26,488	20,951	(9,245)	31,063
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Other Nonoperating Income (Expense)	0	0	0	0
Revenues:
Product	39,849	50,293	73,247	101,346
Service	10,872	15,743	23,740	30,202
Other	0	0	0	0
Revenue	50,721	66,036	96,987	131,548
Expenses:
Cost of products sold	27,171	35,632	51,780	76,300
Operating	9,192	8,822	16,885	16,936
General and administrative	2,379	2,642	4,625	4,706
Depreciation and amortization	9,146	7,255	18,020	14,288
Loss on disposal or impairment of long-lived assets, net	1	(108)		(107)
Loss (gain) on disposal or impairment, net			(13,051)
Total expenses	47,887	54,459	104,361	112,337
Earnings from equity method investments	9,034	15,048	28,214	27,576
Gain (loss) on issuance of common units by equity method investee		0	0	0
Operating income	11,868	26,625	20,840	46,787
Other expenses (income), net:
Interest expense	8,333	6,160	16,336	11,651
Foreign currency transaction loss (gain)	0	0	0	0
Total other expenses, net	8,333	6,160	16,336	11,651
Loss (gain) on sale or impairment of equity method investment	0	0	0	0
Income (loss) from continuing operations before income taxes	3,535	20,465	4,504	35,136
Income tax expense (benefit)	0	0	0	0
Income (loss) from continuing operations	3,535	20,465	4,504	35,136
Loss from discontinued operations, net of income taxes	(1)	(1)	(3)	(1)
Net income	3,534	20,464	4,501	35,135
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to SemGroup	3,534	20,464	4,501	35,135
Other comprehensive income (loss), net of income taxes	485	0	701	0
Comprehensive income (loss)	4,019	20,464	5,202	35,135
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to SemGroup	4,019	20,464	5,202	35,135
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Other Nonoperating Income (Expense)	478	50	664	115
Revenues:
Product	172,798	244,886	379,042	419,938
Service	51,328	50,861	102,533	98,279
Other	15,051	21,886	28,933	38,188
Revenue	239,177	317,633	510,508	556,405
Expenses:
Cost of products sold	152,192	214,969	327,276	372,347
Operating	45,515	51,978	88,014	96,954
General and administrative	13,614	15,649	26,556	28,293
Depreciation and amortization	15,509	17,090	30,302	33,497
Loss on disposal or impairment of long-lived assets, net	(1,686)	(1,264)		(2,323)
Loss (gain) on disposal or impairment, net			(1,941)
Total expenses	228,516	300,950	474,089	533,414
Earnings from equity method investments	17,077	17,683	37,917	38,547
Gain (loss) on issuance of common units by equity method investee		0	0	0
Operating income	27,738	34,366	74,336	61,538
Other expenses (income), net:
Interest expense	11,714	10,614	23,460	19,058
Foreign currency transaction loss (gain)	1,543	(290)	3,012	(809)
Total other expenses, net	12,779	10,274	25,808	18,134
Loss (gain) on sale or impairment of equity method investment	0	0	0	0
Income (loss) from continuing operations before income taxes	14,959	24,092	48,528	43,404
Income tax expense (benefit)	979	2,008	2,957	4,043
Income (loss) from continuing operations	13,980	22,084	45,571	39,361
Loss from discontinued operations, net of income taxes	(1)	(1)	(1)	(1)
Net income	13,979	22,083	45,570	39,360
Less: net income attributable to noncontrolling interests	1,922	5,136	10,942	9,446
Net income (loss) attributable to SemGroup	12,057	16,947	34,628	29,914
Other comprehensive income (loss), net of income taxes	(12,374)	7,866	3,767	(9,840)
Comprehensive income (loss)	1,605	29,949	49,337	29,520
Less: comprehensive income attributable to noncontrolling interests	1,922	5,136	10,942	9,446
Comprehensive income (loss) attributable to SemGroup	(317)	24,813	38,395	20,074
Consolidating Adjustments [Member]
Condensed Income Statements, Captions [Line Items]
Other Nonoperating Income (Expense)	(236)	(733)	(473)	(1,499)
Revenues:
Product	(2,521)	(6,443)	(5,267)	(12,417)
Service	0	0	0	0
Other	0	0	0	0
Revenue	(2,521)	(6,443)	(5,267)	(12,417)
Expenses:
Cost of products sold	(2,521)	(6,443)	(5,267)	(12,417)
Operating	0	0	0	0
General and administrative	0	0	0	0
Depreciation and amortization	0	0	0	0
Loss on disposal or impairment of long-lived assets, net	0	0		0
Loss (gain) on disposal or impairment, net			0
Total expenses	(2,521)	(6,443)	(5,267)	(12,417)
Earnings from equity method investments	(15,590)	(37,411)	(39,129)	(65,049)
Gain (loss) on issuance of common units by equity method investee		0	0	0
Operating income	(15,590)	(37,411)	(39,129)	(65,049)
Other expenses (income), net:
Interest expense	(236)	(733)	(473)	(1,499)
Foreign currency transaction loss (gain)	0	0	0	0
Total other expenses, net	0	0	0	0
Loss (gain) on sale or impairment of equity method investment	0	0	0	0
Income (loss) from continuing operations before income taxes	(15,590)	(37,411)	(39,129)	(65,049)
Income tax expense (benefit)	0	0	0	0
Income (loss) from continuing operations	(15,590)	(37,411)	(39,129)	(65,049)
Loss from discontinued operations, net of income taxes	0	0	0	0
Net income	(15,590)	(37,411)	(39,129)	(65,049)
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to SemGroup	(15,590)	(37,411)	(39,129)	(65,049)
Other comprehensive income (loss), net of income taxes	0	0	0	0
Comprehensive income (loss)	(15,590)	(37,411)	(39,129)	(65,049)
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to SemGroup	$ (15,590)	$ (37,411)	$ (39,129)	$ (65,049)