Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 31, 2019
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Jun. 30, 2019
Entity File Number	1-34736
Entity Registrant Name	SEMGROUP CORPORATION
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-3533152
Entity Address, Address Line One	6120 S. Yale Ave, Suite 1500
Entity Address, City or Town	Tulsa
Entity Address, State or Province	OK
Entity Address, Postal Zip Code	74136-4231
City Area Code	918
Local Phone Number	524-8100
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Class A common stock
Trading Symbol	SEMG
Security Exchange Name	NYSE
Amendment Flag	false
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2019
Entity Central Index Key	0001489136
Current Fiscal Year End Date	--12-31
Common Class A [Member]
Entity Common Stock, Shares Outstanding		79,581,828
Class B
Entity Common Stock, Shares Outstanding		0