NET LOSS PER SHARE - Schedule of basic and diluted net loss per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Net loss	$ (10,863)	$ (91,297)	$ (38,377)	$ (111,633)
Less net income attributable to non-controlling interests	32	0	32	0
Net loss attributable to INAP stockholders	$ (10,895)	$ (91,297)	$ (38,409)	$ (111,633)
Weighted average shares outstanding, basic and diluted (in shares)	79,715	52,096	74,581	52,245
Net loss per share, basic and diluted (in dollars per share)	$ (0.14)	$ (1.75)	$ (0.51)	$ (2.14)
Anti-dilutive securities excluded from diluted net loss per share calculation for stock-based compensation plans (in shares)	5,840	7,238	5,840	7,238