OPERATING SEGMENTS - Summary of operating results for business segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Total revenues	$ 74,201	$ 72,133
Direct costs of sales and services, customer support and sales and marketing, exclusive of depreciation and amortization:
Total direct costs of sales and services, customer support and sales and marketing	41,670	44,459
Business unit contribution:
Total business unit contribution	32,531	27,674
Exit activities, restructuring and impairments	(33)	1,023
Other operating expenses, including depreciation and amortization	31,685	26,159
Income from operations	879	492
Non-operating expenses	14,812	8,234
Loss before income taxes, non-controlling interest and equity in earnings of equity-method investment	(13,933)	(7,742)
INAP US
Revenues:
Total revenues	57,076	55,461
Direct costs of sales and services, customer support and sales and marketing, exclusive of depreciation and amortization:
Total direct costs of sales and services, customer support and sales and marketing	30,537	35,457
Business unit contribution:
Total business unit contribution	26,539	20,004
INAP INTL
Revenues:
Total revenues	17,125	16,672
Direct costs of sales and services, customer support and sales and marketing, exclusive of depreciation and amortization:
Total direct costs of sales and services, customer support and sales and marketing	11,133	9,002
Business unit contribution:
Total business unit contribution	$ 5,992	$ 7,670