GOODWILL AND OTHER INTANGIBLE ASSETS - Summary of Re-Allocations of Goodwill (Details) - USD ($)	3 Months Ended				12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Goodwill, beginning of period				$ 130,313,000	$ 50,209,000	$ 130,313,000
Re-allocations					0	0
Impairment	$ (1,936,000)	$ (78,169,000)	$ 0	0	0	(80,105,000)	$ 0
Goodwill, end of period	50,209,000				50,209,000	50,209,000	130,313,000
Data center services
Goodwill [Roll Forward]
Goodwill, beginning of period				90,849,000	0	90,849,000
Re-allocations					0	(90,849,000)
Impairment						0
Goodwill, end of period	0				0	0	90,849,000
IP services
Goodwill [Roll Forward]
Goodwill, beginning of period				39,464,000	0	39,464,000
Re-allocations					0	(39,464,000)
Impairment						0
Goodwill, end of period	0				0	0	39,464,000
Data center and network services
Goodwill [Roll Forward]
Goodwill, beginning of period				0		0
Re-allocations					0	80,105,000
Impairment						(80,105,000)
Goodwill, end of period					0		0
Cloud and hosting services
Goodwill [Roll Forward]
Goodwill, beginning of period				$ 0	50,209,000	0
Re-allocations					(50,209,000)	50,209,000
Impairment						0
Goodwill, end of period	50,209,000				0	50,209,000	$ 0
INAP COLO
Goodwill [Roll Forward]
Goodwill, beginning of period					0
Re-allocations					6,003,000
Goodwill, end of period	0				6,003,000	0
INAP CLOUD
Goodwill [Roll Forward]
Goodwill, beginning of period					0
Re-allocations					44,206,000
Goodwill, end of period	$ 0				$ 44,206,000	$ 0