Condensed Consolidating Guarantor Financial Statements - Statements of Operations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Revenues:
Product	$ 427,030	$ 235,629
Service	48,507	27,657
Other	23,346	24,410
Revenue	498,883	287,696
Expenses:
Cost of products sold	385,113	212,369
Operating	50,778	40,771
General and administrative	18,736	17,037
Depreciation and amortization	23,637	12,636
Gain on disposal of long-lived assets, net	(58)	(162)
Total expenses	478,206	282,651
Earnings from equity method investments	14,962	17,345
Gain on issuance of common units by equity method investee	8,127	0
Operating income	43,766	22,390
Other expenses (income):
Interest expense	9,227	2,396
Foreign currency transaction gain	(683)	(167)
Other expense (income), net	(1,047)	25,633
Total other expenses, net	7,497	27,862
Income from continuing operations	19,743	48,534
Income tax expense (benefit)	16,526	(54,006)
Income (loss) from continuing operations before income taxes	36,269	(5,472)
Income (loss) from discontinued operations, net of income taxes	(5)	32
Net income	19,738	48,566
Less: net income attributable to noncontrolling interests	6,150	5,143
Net income attributable to SemGroup	13,588	43,423
Other comprehensive loss, net of income taxes	(2,972)	(5,058)
Comprehensive income	16,766	43,508
Less: comprehensive income attributable to noncontrolling interests	6,150	5,143
Comprehensive income attributable to SemGroup	10,616	38,365
Parent Company [Member]
Revenues:
Product	0	0
Service	0	0
Other	0	0
Revenue	0	0
Expenses:
Cost of products sold	0	0
Operating	0	0
General and administrative	4,533	3,918
Depreciation and amortization	435	525
Gain on disposal of long-lived assets, net	0	0
Total expenses	4,968	4,443
Earnings from equity method investments	20,902	16,866
Gain on issuance of common units by equity method investee	8,127
Operating income	24,061	12,423
Other expenses (income):
Interest expense	2,490	(2,016)
Foreign currency transaction gain	0	0
Other expense (income), net	(1,797)	24,434
Total other expenses, net	693	22,418
Income from continuing operations	13,588	43,423
Income tax expense (benefit)	9,780	(53,418)
Income (loss) from continuing operations before income taxes	23,368	(9,995)
Income (loss) from discontinued operations, net of income taxes	0	0
Net income	13,588	43,423
Less: net income attributable to noncontrolling interests	0	0
Net income attributable to SemGroup	13,588	43,423
Other comprehensive loss, net of income taxes	(746)	1,416
Comprehensive income	12,842	44,839
Less: comprehensive income attributable to noncontrolling interests	0	0
Comprehensive income attributable to SemGroup	12,842	44,839
Guarantor Subsidiaries [Member]
Revenues:
Product	98,125	37,634
Service	2,810	248
Other	0	0
Revenue	100,935	37,882
Expenses:
Cost of products sold	77,534	28,474
Operating	7,350	3,971
General and administrative	2,291	2,036
Depreciation and amortization	5,764	1,978
Gain on disposal of long-lived assets, net	10	8
Total expenses	92,949	36,467
Earnings from equity method investments	16,627	18,547
Gain on issuance of common units by equity method investee	0
Operating income	24,613	19,962
Other expenses (income):
Interest expense	4,079	803
Foreign currency transaction gain	0	0
Other expense (income), net	0	158
Total other expenses, net	4,079	961
Income from continuing operations	20,534	19,001
Income tax expense (benefit)	0	0
Income (loss) from continuing operations before income taxes	20,534	19,001
Income (loss) from discontinued operations, net of income taxes	0	30
Net income	20,534	19,031
Less: net income attributable to noncontrolling interests	0	0
Net income attributable to SemGroup	20,534	19,031
Other comprehensive loss, net of income taxes	0	0
Comprehensive income	20,534	19,031
Less: comprehensive income attributable to noncontrolling interests	0	0
Comprehensive income attributable to SemGroup	20,534	19,031
Non-Guarantor Subsidiaries [Member]
Revenues:
Product	338,797	202,064
Service	45,697	27,409
Other	23,346	24,410
Revenue	407,840	253,883
Expenses:
Cost of products sold	317,471	187,964
Operating	43,428	36,800
General and administrative	11,912	11,083
Depreciation and amortization	17,438	10,133
Gain on disposal of long-lived assets, net	(68)	(170)
Total expenses	390,181	245,810
Earnings from equity method investments	7,404	10,439
Gain on issuance of common units by equity method investee	0
Operating income	25,063	18,512
Other expenses (income):
Interest expense	3,475	7,412
Foreign currency transaction gain	(683)	(167)
Other expense (income), net	(67)	(2,762)
Total other expenses, net	2,725	4,483
Income from continuing operations	15,592	14,617
Income tax expense (benefit)	6,746	(588)
Income (loss) from continuing operations before income taxes	22,338	14,029
Income (loss) from discontinued operations, net of income taxes	(5)	2
Net income	15,587	14,619
Less: net income attributable to noncontrolling interests	6,150	5,143
Net income attributable to SemGroup	9,437	9,476
Other comprehensive loss, net of income taxes	(2,226)	(6,474)
Comprehensive income	13,361	8,145
Less: comprehensive income attributable to noncontrolling interests	6,150	5,143
Comprehensive income attributable to SemGroup	7,211	3,002
Consolidation, Eliminations [Member]
Revenues:
Product	(9,892)	(4,069)
Service	0	0
Other	0	0
Revenue	(9,892)	(4,069)
Expenses:
Cost of products sold	(9,892)	(4,069)
Operating	0	0
General and administrative	0	0
Depreciation and amortization	0	0
Gain on disposal of long-lived assets, net	0	0
Total expenses	(9,892)	(4,069)
Earnings from equity method investments	(29,971)	(28,507)
Gain on issuance of common units by equity method investee	0
Operating income	(29,971)	(28,507)
Other expenses (income):
Interest expense	(817)	(3,803)
Foreign currency transaction gain	0	0
Other expense (income), net	817	3,803
Total other expenses, net	0	0
Income from continuing operations	(29,971)	(28,507)
Income tax expense (benefit)	0	0
Income (loss) from continuing operations before income taxes	(29,971)	(28,507)
Income (loss) from discontinued operations, net of income taxes	0	0
Net income	(29,971)	(28,507)
Less: net income attributable to noncontrolling interests	0	0
Net income attributable to SemGroup	(29,971)	(28,507)
Other comprehensive loss, net of income taxes	0	0
Comprehensive income	(29,971)	(28,507)
Less: comprehensive income attributable to noncontrolling interests	0	0
Comprehensive income attributable to SemGroup	$ (29,971)	$ (28,507)