PROPERTY AND EQUIPMENT, NET (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 278,762	$ 263,179
Less accumulated depreciation and amortization	(177,808)	(157,455)
Property and equipment, net	100,954	105,724	104,613
Operations equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	93,776	92,560
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	10,709	10,829
Office equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	4,027	4,280
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	34,792	31,684
Capitalized software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	119,027	109,891
Construction in progress
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	16,431	12,759
Building
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 0	$ 1,176