Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Mar. 13, 2019	Jun. 30, 2018
Document and Entity Information Abstract
Entity Registrant Name	Internap Corp
Entity Central Index Key	0001056386
Trading Symbol	inap
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		25,397,126
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 151,640,134
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false