PROPERTY AND EQUIPMENT (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
PROPERTY AND EQUIPMENT
Property and equipment, gross	$ 147,532	$ 138,877
Less: accumulated depreciation and amortization	(94,402)	(85,529)
Total property and equipment, net	53,130	53,348
Computer equipment
PROPERTY AND EQUIPMENT
Property and equipment, gross	19,987	18,269
Capitalized software
PROPERTY AND EQUIPMENT
Property and equipment, gross	82,547	78,036
Land, buildings and leasehold improvements
PROPERTY AND EQUIPMENT
Property and equipment, gross	25,517	23,781
Furniture and other equipment
PROPERTY AND EQUIPMENT
Property and equipment, gross	13,575	12,419
Projects in progress
PROPERTY AND EQUIPMENT
Property and equipment, gross	$ 5,906	$ 6,372