Condensed Consolidating Guarantor Financial Statements - Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Condensed Income Statements, Captions [Line Items]
Other Nonoperating Income (Expense)	$ 150	$ 188
Revenues:
Product	373,361	236,896
Service	68,193	64,073
Other	14,546	13,882
Revenue	456,100	314,851
Expenses:
Cost of products sold	348,998	196,947
Operating	52,083	50,192
General and administrative	21,644	21,060
Depreciation and amortization	24,599	24,051
Loss on disposal or impairment of long-lived assets, net	(2,410)	(13,307)
Total expenses	449,734	305,557
Earnings from equity method investments	17,091	23,071
Loss on issuance of common units by equity method investee	0	(41)
Operating income	23,457	32,324
Other expenses (income), net:
Interest expense	13,867	17,577
Loss on early extinguishment of debt	19,922	0
Foreign currency transaction loss	0	1,469
Total other expenses, net	33,639	58,622
Loss on sale or impairment of equity method investment	0	39,764
Income (loss) from continuing operations before income taxes	(10,182)	(26,298)
Income tax expense (benefit)	95	(21,407)
Income (loss) from continuing operations	(10,277)	(4,891)
Loss from discontinued operations, net of income taxes	0	(2)
Net loss	(10,277)	(4,893)
Less: net income attributable to noncontrolling interests	0	9,020
Net income (loss) attributable to SemGroup	(10,277)	(13,913)
Other comprehensive income (loss), net of income taxes	6,033	(4,109)
Comprehensive income (loss)	(4,244)	(9,002)
Less: comprehensive income attributable to noncontrolling interests	0	9,020
Comprehensive income (loss) attributable to SemGroup	(4,244)	(18,022)
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Other Nonoperating Income (Expense)	197	237
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	5,930	5,872
Depreciation and amortization	473	380
Loss on disposal or impairment of long-lived assets, net	0	0
Total expenses	6,403	6,252
Earnings from equity method investments	19,187	7,106
Loss on issuance of common units by equity method investee		(41)
Operating income	12,784	813
Other expenses (income), net:
Interest expense	5,866	(1,416)
Loss on early extinguishment of debt	19,922
Foreign currency transaction loss		0
Total other expenses, net	25,591	38,111
Loss on sale or impairment of equity method investment		39,764
Income (loss) from continuing operations before income taxes	(12,807)	(37,298)
Income tax expense (benefit)	(2,530)	(23,385)
Income (loss) from continuing operations		(13,913)
Loss from discontinued operations, net of income taxes		0
Net loss	(10,277)	(13,913)
Less: net income attributable to noncontrolling interests		0
Net income (loss) attributable to SemGroup		(13,913)
Other comprehensive income (loss), net of income taxes	(3,581)	(20,466)
Comprehensive income (loss)	(13,858)	(34,379)
Less: comprehensive income attributable to noncontrolling interests		0
Comprehensive income (loss) attributable to SemGroup		(34,379)
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Other Nonoperating Income (Expense)	2	0
Revenues:
Product	340,788	207,274
Service	38,050	50,156
Other	0	0
Revenue	378,838	257,430
Expenses:
Cost of products sold	321,657	183,213
Operating	28,120	29,100
General and administrative	6,930	7,148
Depreciation and amortization	16,830	16,771
Loss on disposal or impairment of long-lived assets, net	(1,982)	(13,346)
Total expenses	375,519	249,578
Earnings from equity method investments	18,566	21,028
Loss on issuance of common units by equity method investee		0
Operating income	21,885	28,880
Other expenses (income), net:
Interest expense	8,820	20,440
Loss on early extinguishment of debt	0
Foreign currency transaction loss		0
Total other expenses, net	8,818	20,440
Loss on sale or impairment of equity method investment		0
Income (loss) from continuing operations before income taxes	13,067	8,440
Income tax expense (benefit)	0	0
Income (loss) from continuing operations		8,440
Loss from discontinued operations, net of income taxes		(2)
Net loss	13,067	8,438
Less: net income attributable to noncontrolling interests		9,020
Net income (loss) attributable to SemGroup		(582)
Other comprehensive income (loss), net of income taxes	(74)	216
Comprehensive income (loss)	12,993	8,654
Less: comprehensive income attributable to noncontrolling interests		9,020
Comprehensive income (loss) attributable to SemGroup		(366)
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Other Nonoperating Income (Expense)	144	188
Revenues:
Product	32,573	29,622
Service	30,143	13,917
Other	14,546	13,882
Revenue	77,262	57,421
Expenses:
Cost of products sold	27,341	13,734
Operating	23,963	21,092
General and administrative	8,784	8,040
Depreciation and amortization	7,296	6,900
Loss on disposal or impairment of long-lived assets, net	(428)	39
Total expenses	67,812	49,727
Earnings from equity method investments	0	0
Loss on issuance of common units by equity method investee		0
Operating income	9,450	7,694
Other expenses (income), net:
Interest expense	(626)	(1,210)
Loss on early extinguishment of debt	0
Foreign currency transaction loss		1,469
Total other expenses, net	(770)	71
Loss on sale or impairment of equity method investment		0
Income (loss) from continuing operations before income taxes	10,220	7,623
Income tax expense (benefit)	2,625	1,978
Income (loss) from continuing operations		5,645
Loss from discontinued operations, net of income taxes		0
Net loss	7,595	5,645
Less: net income attributable to noncontrolling interests		0
Net income (loss) attributable to SemGroup		5,645
Other comprehensive income (loss), net of income taxes	9,688	16,141
Comprehensive income (loss)	17,283	21,786
Less: comprehensive income attributable to noncontrolling interests		0
Comprehensive income (loss) attributable to SemGroup		21,786
Consolidating Adjustments [Member]
Condensed Income Statements, Captions [Line Items]
Other Nonoperating Income (Expense)	(193)	(237)
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	0	0
Depreciation and amortization	0	0
Loss on disposal or impairment of long-lived assets, net	0	0
Total expenses	0	0
Earnings from equity method investments	(20,662)	(5,063)
Loss on issuance of common units by equity method investee		0
Operating income	(20,662)	(5,063)
Other expenses (income), net:
Interest expense	(193)	(237)
Loss on early extinguishment of debt	0
Foreign currency transaction loss		0
Total other expenses, net	0	0
Loss on sale or impairment of equity method investment		0
Income (loss) from continuing operations before income taxes	(20,662)	(5,063)
Income tax expense (benefit)	0	0
Income (loss) from continuing operations		(5,063)
Loss from discontinued operations, net of income taxes		0
Net loss	(20,662)	(5,063)
Less: net income attributable to noncontrolling interests		0
Net income (loss) attributable to SemGroup		(5,063)
Other comprehensive income (loss), net of income taxes	0	0
Comprehensive income (loss)	$ (20,662)	(5,063)
Less: comprehensive income attributable to noncontrolling interests		0
Comprehensive income (loss) attributable to SemGroup		$ (5,063)