Condensed Consolidating Guarantor Financial Statements - Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenues:
Product	$ 313,351	$ 495,436	$ 822,218	$ 1,325,452
Service	64,091	65,219	192,572	167,176
Other	19,623	33,580	57,811	82,714
Revenue	397,065	594,235	1,072,601	1,575,342
Expenses:
Cost of products sold	274,639	458,063	710,869	1,211,703
Operating	53,267	69,377	167,157	179,579
General and administrative	23,045	23,296	78,272	63,882
Depreciation and amortization	26,022	25,200	74,430	70,899
Loss (gain) on disposal of long-lived assets, net	(951)	1,376	1,479	20,633
Total expenses	376,022	577,312	1,032,207	1,546,696
Earnings from equity method investments	16,237	14,223	60,699	48,372
Gain on issuance of common units by equity method investee	136	18,772	6,033	26,899
Operating income	37,416	49,918	107,126	103,917
Other expenses (income), net:
Interest expense	19,170	14,807	50,583	34,394
Foreign currency transaction loss (gain)	(385)	128	(1,199)	(388)
Other income, net	(956)	(21,303)	(15,659)	(3,388)
Total other expenses, net	17,829	(6,368)	33,725	30,618
Income (loss) from continuing operations before income taxes	19,587	56,286	73,401	73,299
Income tax expense	10,006	24,090	29,609	33,944
Income (loss) from continuing operations	9,581	32,196	43,792	39,355
Loss from discontinued operations, net of income taxes	(1)	0	(3)	(5)
Net income	9,580	32,196	43,789	39,350
Less: net income attributable to noncontrolling interests	4,707	6,934	14,153	18,184
Net income (loss) attributable to SemGroup	4,873	25,262	29,636	21,166
Other comprehensive loss, net of income taxes	(20,210)	(10,331)	(23,750)	(6,618)
Comprehensive income (loss)	(10,630)	21,865	20,039	32,732
Less: comprehensive income attributable to noncontrolling interests	4,707	6,934	14,153	18,184
Comprehensive income (loss) attributable to SemGroup	(15,337)	14,931	5,886	14,548
Parent Company [Member]
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	4,730	7,862	26,958	17,380
Depreciation and amortization	423	430	1,046	1,282
Loss (gain) on disposal of long-lived assets, net	0	0	0	5,945
Total expenses	5,153	8,292	28,004	24,607
Earnings from equity method investments	15,416	15,778	58,804	47,097
Gain on issuance of common units by equity method investee	136	18,772	6,033	26,899
Operating income	10,399	26,258	36,833	49,389
Other expenses (income), net:
Interest expense	185	1,658	2,388	7,241
Foreign currency transaction loss (gain)	0	0	(5)	0
Other income, net	(246)	(22,030)	(16,333)	(5,729)
Total other expenses, net	(61)	(20,372)	(13,950)	1,512
Income (loss) from continuing operations before income taxes	10,460	46,630	50,783	47,877
Income tax expense	5,587	21,368	21,147	26,711
Income (loss) from continuing operations	4,873		29,636	21,166
Loss from discontinued operations, net of income taxes	0		0	0
Net income	4,873	25,262	29,636	21,166
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to SemGroup	4,873	25,262	29,636	21,166
Other comprehensive loss, net of income taxes	7,055	3,377	13,355	951
Comprehensive income (loss)	11,928	28,639	42,991	22,117
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to SemGroup	11,928	28,639	42,991	22,117
Guarantor Subsidiaries [Member]
Revenues:
Product	49,129	83,442	150,475	263,779
Service	15,141	12,320	45,343	23,132
Other	0	0	0	0
Revenue	64,270	95,762	195,818	286,911
Expenses:
Cost of products sold	36,345	67,929	112,645	212,769
Operating	8,507	9,031	25,443	24,127
General and administrative	2,376	2,323	7,082	6,624
Depreciation and amortization	8,462	6,893	22,750	18,823
Loss (gain) on disposal of long-lived assets, net	35	(7)	142	54,698
Total expenses	55,725	86,169	168,062	317,041
Earnings from equity method investments	13,936	5,879	41,512	65,658
Gain on issuance of common units by equity method investee	0	0	0	0
Operating income	22,481	15,472	69,268	35,528
Other expenses (income), net:
Interest expense	7,215	2,330	18,866	6,727
Foreign currency transaction loss (gain)	0	0	0	0
Other income, net	0	0	0	0
Total other expenses, net	7,215	2,330	18,866	6,727
Income (loss) from continuing operations before income taxes	15,266	13,142	50,402	28,801
Income tax expense	0	0	0	0
Income (loss) from continuing operations	15,266		50,402	28,801
Loss from discontinued operations, net of income taxes	0		(1)	0
Net income	15,266	13,142	50,401	28,801
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to SemGroup	15,266	13,142	50,401	28,801
Other comprehensive loss, net of income taxes	251	0	251	0
Comprehensive income (loss)	15,517	13,142	50,652	28,801
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to SemGroup	15,517	13,142	50,652	28,801
Non-Guarantor Subsidiaries [Member]
Revenues:
Product	268,384	421,704	688,322	1,091,050
Service	48,950	52,899	147,229	144,044
Other	19,623	33,580	57,811	82,714
Revenue	336,957	508,183	893,362	1,317,808
Expenses:
Cost of products sold	242,456	399,844	614,803	1,028,311
Operating	44,760	60,346	141,714	155,452
General and administrative	15,939	13,111	44,232	39,878
Depreciation and amortization	17,137	17,877	50,634	50,794
Loss (gain) on disposal of long-lived assets, net	(986)	1,383	1,337	(40,010)
Total expenses	319,306	492,561	852,720	1,234,425
Earnings from equity method investments	17,116	18,705	55,663	36,537
Gain on issuance of common units by equity method investee	0	0	0	0
Operating income	34,767	34,327	96,305	119,920
Other expenses (income), net:
Interest expense	11,998	11,650	31,056	22,906
Foreign currency transaction loss (gain)	(385)	128	(1,194)	(388)
Other income, net	(938)	(104)	(1,053)	(139)
Total other expenses, net	10,675	11,674	28,809	22,379
Income (loss) from continuing operations before income taxes	24,092	22,653	67,496	97,541
Income tax expense	4,419	2,722	8,462	7,233
Income (loss) from continuing operations	19,673		59,034	90,308
Loss from discontinued operations, net of income taxes	(1)		(2)	(5)
Net income	19,672	19,931	59,032	90,303
Less: net income attributable to noncontrolling interests	4,707	6,934	14,153	18,184
Net income (loss) attributable to SemGroup	14,965	12,997	44,879	72,119
Other comprehensive loss, net of income taxes	(27,516)	(13,708)	(37,356)	(7,569)
Comprehensive income (loss)	(7,844)	6,223	21,676	82,734
Less: comprehensive income attributable to noncontrolling interests	4,707	6,934	14,153	18,184
Comprehensive income (loss) attributable to SemGroup	(12,551)	(711)	7,523	64,550
Consolidation, Eliminations [Member]
Revenues:
Product	(4,162)	(9,710)	(16,579)	(29,377)
Service	0	0	0	0
Other	0	0	0	0
Revenue	(4,162)	(9,710)	(16,579)	(29,377)
Expenses:
Cost of products sold	(4,162)	(9,710)	(16,579)	(29,377)
Operating	0	0	0	0
General and administrative	0	0	0	0
Depreciation and amortization	0	0	0	0
Loss (gain) on disposal of long-lived assets, net	0	0	0	0
Total expenses	(4,162)	(9,710)	(16,579)	(29,377)
Earnings from equity method investments	(30,231)	(26,139)	(95,280)	(100,920)
Gain on issuance of common units by equity method investee	0	0	0	0
Operating income	(30,231)	(26,139)	(95,280)	(100,920)
Other expenses (income), net:
Interest expense	(228)	(831)	(1,727)	(2,480)
Foreign currency transaction loss (gain)	0	0	0	0
Other income, net	228	831	1,727	2,480
Total other expenses, net	0	0	0	0
Income (loss) from continuing operations before income taxes	(30,231)	(26,139)	(95,280)	(100,920)
Income tax expense	0	0	0	0
Income (loss) from continuing operations	(30,231)		(95,280)	(100,920)
Loss from discontinued operations, net of income taxes	0		0	0
Net income	(30,231)	(26,139)	(95,280)	(100,920)
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to SemGroup	(30,231)	(26,139)	(95,280)	(100,920)
Other comprehensive loss, net of income taxes	0	0	0	0
Comprehensive income (loss)	(30,231)	(26,139)	(95,280)	(100,920)
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to SemGroup	$ (30,231)	$ (26,139)	$ (95,280)	$ (100,920)