Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2012	Feb. 12, 2013	Jun. 30, 2012
Document and Entity Information Abstract
Entity Registrant Name	INTERNAP NETWORK SERVICES CORP
Entity Central Index Key	0001056386
Trading Symbol	inap
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Well-Known Seasoned Issuer	No
Entity Common Stock Shares Outstanding		53,514,415
Entity Public Float			$ 304,278,552
Document Type	10-K
Document Period End Date	Dec. 31, 2012
Amendment Flag	false
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY