OPERATING SEGMENTS AND GEOGRAPHIC INFORMATION - Revenue by Source (Details) - USD ($)	3 Months Ended								12 Months Ended			50 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 78,238,000	$ 82,972,000	$ 81,962,000	$ 74,201,000	$ 70,035,000	$ 68,907,000	$ 69,642,000	$ 72,133,000	$ 317,373,000	$ 280,718,000	$ 298,297,000	$ 8,855
Colocation
Disaggregation of Revenue [Line Items]
Revenues									131,124,000	124,083,000	129,881,000
Network Services
Disaggregation of Revenue [Line Items]
Revenues									64,111,000	67,435,000	70,779,000
Cloud
Disaggregation of Revenue [Line Items]
Revenues									122,138,000	89,200,000	97,637,000
INAP US
Disaggregation of Revenue [Line Items]
Revenues									248,184,000	215,770,000	229,902,000
INAP US | Colocation
Disaggregation of Revenue [Line Items]
Revenues									125,282,000
INAP US | Network Services
Disaggregation of Revenue [Line Items]
Revenues									52,748,000
INAP US | Cloud
Disaggregation of Revenue [Line Items]
Revenues									70,154,000
INAP INTL
Disaggregation of Revenue [Line Items]
Revenues									69,189,000	$ 64,948,000	$ 68,395,000
INAP INTL | Colocation
Disaggregation of Revenue [Line Items]
Revenues									5,842,000
INAP INTL | Network Services
Disaggregation of Revenue [Line Items]
Revenues									11,363,000
INAP INTL | Cloud
Disaggregation of Revenue [Line Items]
Revenues									$ 51,984,000