OPERATING SEGMENTS - Summary of operating results for business segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues:
Total revenues	$ 72,878	$ 82,972	$ 219,576	$ 239,135
Cost of sales and services, customer support and sales and marketing:
Total costs of sales and services, customer support and sales and marketing	43,068	46,675	127,672	134,015
Segment profit:
Total segment profit	29,810	36,297	91,904	105,120
Exit activities, restructuring and impairments	3,792	2,347	5,439	3,140
Other operating expenses, including sales, general and administrative and depreciation and amortization expenses	29,954	31,253	91,885	95,404
(Loss) income from operations	(3,936)	2,697	(5,420)	6,576
Non-operating expenses	19,919	17,989	56,906	50,143
Loss before income taxes and equity in earnings of equity-method investment	(23,855)	(15,292)	(62,326)	(43,567)
INAP US
Revenues:
Total revenues	56,947	65,678	171,928	186,821
Cost of sales and services, customer support and sales and marketing:
Total costs of sales and services, customer support and sales and marketing	32,920	35,197	97,780	99,532
Segment profit:
Total segment profit	24,027	30,481	74,148	87,289
INAP INTL
Revenues:
Total revenues	15,931	17,294	47,648	52,314
Cost of sales and services, customer support and sales and marketing:
Total costs of sales and services, customer support and sales and marketing	10,148	11,478	29,892	34,483
Segment profit:
Total segment profit	$ 5,783	$ 5,816	$ 17,756	$ 17,831