NATURE OF OPERATIONS AND BASIS OF PRESENTATION - Adjustments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Costs of sales and services, exclusive of depreciation and amortization	$ 27,504	$ 28,221	$ 79,186	$ 80,160
Depreciation and amortization	21,582	23,553	65,715	67,422
Interest expense	19,913	17,794	56,578	50,138
Net loss attributable to INAP shareholders	(23,870)	(15,479)	(62,069)	(44,046)
Property and equipment, net	216,548	487,616	216,548	487,616			$ 478,061
Total assets	724,701	756,231	724,701	756,231			744,931
Capital lease obligations	0	263,676	0	263,676			9,080
Total liabilities	784,913	776,154	784,913	776,154			744,874
Accumulated deficit	(1,425,140)	(1,344,566)	(1,425,140)	(1,344,566)			(1,363,019)
Total stockholders’ (deficit) equity	$ (60,212)	(19,923)	$ (60,212)	(19,923)	$ (37,533)	$ (19,972)	$ 57	$ (5,605)	$ 8,594	$ (1,032)
As reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Costs of sales and services, exclusive of depreciation and amortization		28,866		81,880
Depreciation and amortization		23,431		67,097
Interest expense		16,898		47,786
Net loss attributable to INAP shareholders		(15,106)		(43,089)
Property and equipment, net		477,423		477,423
Total assets		746,038		746,038
Capital lease obligations		252,599		252,599
Total liabilities		765,004		765,004
Accumulated deficit		(1,343,609)		(1,343,609)
Total stockholders’ (deficit) equity		(18,966)		(18,966)
Adjustments | Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Costs of sales and services, exclusive of depreciation and amortization		(645)		(1,720)
Depreciation and amortization		122		325
Interest expense		896		2,352
Net loss attributable to INAP shareholders		(373)		(957)
Property and equipment, net		10,193		10,193
Total assets		10,193		10,193
Capital lease obligations		11,077		11,077
Total liabilities		11,150		11,150
Accumulated deficit		(957)		(957)
Total stockholders’ (deficit) equity		$ (957)		$ (957)