OPERATING SEGMENTS AND GEOGRAPHIC INFORMATION - Summary of Operating Results for Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Revenues	$ 71,650	$ 72,960	$ 73,022	$ 73,873	$ 77,155	$ 82,928	$ 82,253	$ 73,822	$ 146,668	$ 156,075	$ 219,628	$ 239,003	$ 291,505	$ 316,158	$ 280,718
Costs of sales and services, customer support and sales and marketing:
Costs of sales and services, customer support and sales and marketing:													168,599	180,303	165,891
Segment profit:
Segment profit													122,906	135,855	114,827
Goodwill and intangibles impairment													59,126	0	0
Exit activities, restructuring and impairments	$ 3,547	$ 3,792	$ 231	$ 1,416	$ 2,266	$ 2,347	$ 826	$ (33)					8,986	5,406	6,249
Other operating expenses, including sales, general and administrative and depreciation and amortization expenses													123,221	123,302	102,240
(Loss) income from operations													(68,427)	7,147	6,338
Non-operating expenses													71,390	67,565	51,458
Loss before income taxes and equity in earnings of equity-method investment													(139,817)	(60,418)	(45,120)
INAP US
Revenues:
Revenues													228,744	247,146	215,770
Costs of sales and services, customer support and sales and marketing:
Costs of sales and services, customer support and sales and marketing:													129,329	135,179	128,062
Segment profit:
Segment profit													99,415	111,967	87,708
INAP INTL
Revenues:
Revenues													62,761	69,012	64,948
Costs of sales and services, customer support and sales and marketing:
Costs of sales and services, customer support and sales and marketing:													39,270	45,124	37,829
Segment profit:
Segment profit													$ 23,491	$ 23,888	$ 27,119