PROPERTY AND EQUIPMENT - Summary of depreciation and amortization of property and equipment associated with direct costs of network, sales and services and other depreciation expense (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Property, Plant and Equipment [Abstract]
Direct costs of network, sales and services									$ 33,019	$ 36,040	$ 26,930
Other depreciation and amortization									3,128	886	3,228
Subtotal									36,147	36,926	30,158
Amortization of acquired technologies	1,179	1,179	1,179	1,179	875	875	875	875	4,718	3,500	3,811
Total depreciation and amortization									$ 40,865	$ 40,426	$ 33,969