OPERATING SEGMENTS - Summary of operating results for business segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Total revenues	$ 82,972	$ 68,907	$ 239,135	$ 210,682
Cost of sales and services, customer support and sales and marketing:
Total costs of sales and services, customer support and sales and marketing	47,320	39,474	135,735	125,171
Segment profit:
Total segment profit	35,652	29,433	103,400	85,511
Exit activities, restructuring and impairments	2,347	745	3,140	6,396
Other operating expenses, including sales, general and administrative and depreciation and amortization expenses	31,131	27,956	95,079	79,944
Income from operations	2,174	732	5,181	(829)
Non-operating expenses	17,093	12,496	47,791	38,066
Loss before income taxes, non-controlling interest and equity in earnings of equity-method investment	(14,919)	(11,764)	(42,610)	(38,895)
INAP US
Revenues:
Total revenues	65,678	52,970	186,821	162,544
Cost of sales and services, customer support and sales and marketing:
Total costs of sales and services, customer support and sales and marketing	35,842	29,600	101,252	97,832
Segment profit:
Total segment profit	29,836	23,370	85,569	64,712
INAP INTL
Revenues:
Total revenues	17,294	15,937	52,314	48,138
Cost of sales and services, customer support and sales and marketing:
Total costs of sales and services, customer support and sales and marketing	11,478	9,874	34,483	27,339
Segment profit:
Total segment profit	$ 5,816	$ 6,063	$ 17,831	$ 20,799