SEGMENT INFORMATION - Segment Performance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of our segment performance measure to income (loss) before income taxes
Segment performance measure	$ 149,072	$ 137,175	$ 138,409
Unallocated expenses	(45,821)	(62,557)	(47,587)
Share-based compensation expense	(13,748)	(13,098)	(10,008)
Depreciation and software and leasehold amortization	(37,810)	(36,042)	(30,971)
Amortization of identifiable intangible assets	(18,347)	(12,655)	(18,834)
Intangible asset impairment expense	(1,162)
Fair value adjustment to contingent consideration	1,182	(1,142)	(2,580)
Other operating income (expense)	(5,291)	(880)	791
Operating income	28,075	10,801	29,220
Interest expense, net	(20,413)	(16,653)	(12,115)
Income (loss) before income taxes	$ 7,662	$ (5,852)	$ 17,105