Condensed Consolidating Guarantor Financial Statements - Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Condensed Income Statements, Captions [Line Items]
Other Nonoperating Income (Expense)	$ 492	$ 956	$ 1,170	$ 1,142
Revenues:
Product	245,920	313,351	692,942	822,218
Service	66,074	64,091	192,347	192,572
Other	15,770	19,623	44,703	57,811
Revenue	327,764	397,065	929,992	1,072,601
Expenses:
Cost of products sold	218,503	274,639	592,292	710,869
Operating	52,636	53,267	157,537	167,157
General and administrative	20,583	23,045	62,419	78,272
Depreciation and amortization	24,912	26,022	74,007	74,430
Loss on disposal or impairment of long-lived assets, net	(1,018)	951		(1,479)
Loss (gain) on disposal or impairment, net	(1,018)	951	(16,010)	(1,479)
Total expenses	317,652	376,022	902,265	1,032,207
Earnings from equity method investments	15,845	16,237	55,994	60,699
Gain (loss) on issuance of common units by equity method investee	0	136	(41)	6,033
Operating income	25,957	37,416	83,680	107,126
Other expenses (income), net:
Interest expense	21,032	19,170	58,842	50,583
Foreign currency transaction loss (gain)	659	(385)	3,671	(1,199)
Total other expenses, net	21,199	17,829	91,987	33,725
Loss (gain) on sale or impairment of equity method investment	0	0	30,644	(14,517)
Income (loss) from continuing operations before income taxes	4,758	19,587	(8,307)	73,401
Income tax expense (benefit)	11,898	10,006	(4,851)	29,609
Income (loss) from continuing operations	(7,140)	9,581	(3,456)	43,792
Loss from discontinued operations, net of income taxes	0	(1)	(1)	(3)
Net income (loss)	(7,140)	9,580	(3,457)	43,789
Less: net income attributable to noncontrolling interests	225	4,707	11,167	14,153
Net income (loss) attributable to SemGroup	(7,365)	4,873	(14,624)	29,636
Other comprehensive loss, net of income taxes	(7,051)	(20,210)	(4,569)	(23,750)
Comprehensive income (loss)	(14,191)	(10,630)	(8,026)	20,039
Less: comprehensive income attributable to noncontrolling interests	225	4,707	11,167	14,153
Comprehensive income (loss) attributable to SemGroup	(14,416)	(15,337)	(19,193)	5,886
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Other Nonoperating Income (Expense)	372	246	859	1,816
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	4,577	4,730	15,230	26,958
Depreciation and amortization	439	423	1,212	1,046
Loss on disposal or impairment of long-lived assets, net	0	0		0
Loss (gain) on disposal or impairment, net			0
Total expenses	5,016	5,153	16,442	28,004
Earnings from equity method investments	6,027	15,416	19,173	58,804
Gain (loss) on issuance of common units by equity method investee		136	(41)	6,033
Operating income	1,011	10,399	2,690	36,833
Other expenses (income), net:
Interest expense	(1,231)	185	(2,744)	2,388
Foreign currency transaction loss (gain)	0	0	0	(5)
Total other expenses, net	(1,603)	(61)	27,041	(13,950)
Loss (gain) on sale or impairment of equity method investment			30,644	(14,517)
Income (loss) from continuing operations before income taxes	2,614	10,460	(24,351)	50,783
Income tax expense (benefit)	9,979	5,587	(9,727)	21,147
Income (loss) from continuing operations		4,873	(14,624)	29,636
Loss from discontinued operations, net of income taxes		0	0	0
Net income (loss)	(7,365)	4,873	(14,624)	29,636
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to SemGroup	(7,365)	4,873	(14,624)	29,636
Other comprehensive loss, net of income taxes	3,711	7,055	1,725	13,355
Comprehensive income (loss)	(3,654)	11,928	(12,899)	42,991
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to SemGroup	(3,654)	11,928	(12,899)	42,991
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Other Nonoperating Income (Expense)	(63)	9	(63)	14
Revenues:
Product	209,835	256,848	597,638	645,869
Service	39,398	47,383	116,410	142,772
Other	0	0	0	0
Revenue	249,233	304,231	714,048	788,641
Expenses:
Cost of products sold	188,329	230,464	514,996	571,000
Operating	29,212	27,561	87,232	88,974
General and administrative	9,558	6,715	24,512	23,371
Depreciation and amortization	17,375	19,096	51,522	54,135
Loss on disposal or impairment of long-lived assets, net	(1,018)	(62)		(299)
Loss (gain) on disposal or impairment, net			(16,077)
Total expenses	245,492	283,898	694,339	737,779
Earnings from equity method investments	19,658	8,603	60,341	58,592
Gain (loss) on issuance of common units by equity method investee		0	0	0
Operating income	23,399	28,936	80,050	109,454
Other expenses (income), net:
Interest expense	23,060	19,706	64,267	49,560
Foreign currency transaction loss (gain)	(18)	0	(18)	0
Total other expenses, net	23,105	19,697	64,312	49,546
Loss (gain) on sale or impairment of equity method investment			0	0
Income (loss) from continuing operations before income taxes	294	9,239	15,738	59,908
Income tax expense (benefit)	0	0	0	0
Income (loss) from continuing operations		9,239	15,738	59,908
Loss from discontinued operations, net of income taxes		0	0	(1)
Net income (loss)	294	9,239	15,738	59,907
Less: net income attributable to noncontrolling interests	225	4,707	11,167	14,153
Net income (loss) attributable to SemGroup	69	4,532	4,571	45,754
Other comprehensive loss, net of income taxes	208	251	909	251
Comprehensive income (loss)	502	9,490	16,647	60,158
Less: comprehensive income attributable to noncontrolling interests	225	4,707	11,167	14,153
Comprehensive income (loss) attributable to SemGroup	277	4,783	5,480	46,005
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Other Nonoperating Income (Expense)	422	929	1,086	1,039
Revenues:
Product	36,085	56,503	95,304	176,349
Service	26,676	16,708	75,937	49,800
Other	15,770	19,623	44,703	57,811
Revenue	78,531	92,834	215,944	283,960
Expenses:
Cost of products sold	30,174	44,175	77,296	139,869
Operating	23,424	25,706	70,305	78,183
General and administrative	6,448	11,600	22,677	27,943
Depreciation and amortization	7,098	6,503	21,273	19,249
Loss on disposal or impairment of long-lived assets, net	0	1,013		(1,180)
Loss (gain) on disposal or impairment, net			67
Total expenses	67,144	86,971	191,484	266,424
Earnings from equity method investments	0	0	0	0
Gain (loss) on issuance of common units by equity method investee		0	0	0
Operating income	11,387	5,863	24,460	17,536
Other expenses (income), net:
Interest expense	(558)	(493)	(1,969)	362
Foreign currency transaction loss (gain)	677	(385)	3,689	(1,194)
Total other expenses, net	(303)	(1,807)	634	(1,871)
Loss (gain) on sale or impairment of equity method investment			0	0
Income (loss) from continuing operations before income taxes	11,690	7,670	23,826	19,407
Income tax expense (benefit)	1,919	4,419	4,876	8,462
Income (loss) from continuing operations		3,251	18,950	10,945
Loss from discontinued operations, net of income taxes		(1)	(1)	(2)
Net income (loss)	9,771	3,250	18,949	10,943
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to SemGroup	9,771	3,250	18,949	10,943
Other comprehensive loss, net of income taxes	(10,970)	(27,516)	(7,203)	(37,356)
Comprehensive income (loss)	(1,199)	(24,266)	11,746	(26,413)
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to SemGroup	(1,199)	(24,266)	11,746	(26,413)
Consolidating Adjustments [Member]
Condensed Income Statements, Captions [Line Items]
Other Nonoperating Income (Expense)	(239)	(228)	(712)	(1,727)
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	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	0	0	0	0
Earnings from equity method investments	(9,840)	(7,782)	(23,520)	(56,697)
Gain (loss) on issuance of common units by equity method investee		0	0	0
Operating income	(9,840)	(7,782)	(23,520)	(56,697)
Other expenses (income), net:
Interest expense	(239)	(228)	(712)	(1,727)
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
Income (loss) from continuing operations before income taxes	(9,840)	(7,782)	(23,520)	(56,697)
Income tax expense (benefit)	0	0	0	0
Income (loss) from continuing operations		(7,782)	(23,520)	(56,697)
Loss from discontinued operations, net of income taxes		0	0	0
Net income (loss)	(9,840)	(7,782)	(23,520)	(56,697)
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to SemGroup	(9,840)	(7,782)	(23,520)	(56,697)
Other comprehensive loss, net of income taxes	0	0	0	0
Comprehensive income (loss)	(9,840)	(7,782)	(23,520)	(56,697)
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to SemGroup	$ (9,840)	$ (7,782)	$ (23,520)	$ (56,697)