OPERATING SEGMENTS - Summary of operating results for business segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues:
Total revenues	$ 81,962	$ 69,642	$ 156,163	$ 141,775
Cost of sales and services, customer support and sales and marketing:
Total costs of sales and services, customer support and sales and marketing	46,745	41,239	88,401	85,697
Segment profit:
Total segment profit	35,217	28,403	67,762	56,078
Exit activities, restructuring and impairments	826	4,628	793	5,651
Other operating expenses, including sales, general and administrative and depreciation and amortization expenses	32,264	25,828	63,963	51,988
Income from operations	2,127	(2,053)	3,006	(1,561)
Non-operating expenses	15,886	17,336	30,698	25,570
Loss before income taxes, non-controlling interest and equity in earnings of equity-method investment	(13,759)	(19,389)	(27,692)	(27,131)
INAP US
Revenues:
Total revenues	64,067	54,113	121,142	109,575
Cost of sales and services, customer support and sales and marketing:
Total costs of sales and services, customer support and sales and marketing	34,873	32,776	65,396	68,232
Segment profit:
Total segment profit	29,194	21,337	55,746	41,343
INAP INTL
Revenues:
Total revenues	17,895	15,529	35,021	32,200
Cost of sales and services, customer support and sales and marketing:
Total costs of sales and services, customer support and sales and marketing	11,872	8,463	23,005	17,465
Segment profit:
Total segment profit	$ 6,023	$ 7,066	$ 12,016	$ 14,735