NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - General (Details ) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Goodwill
Goodwill impairment charge		$ 153
Goodwill		477,479	$ 404,187	$ 404,302
Intangible Assets
Impairment of identifiable intangible assets	$ 1,000
Accounts Receivable
Allowance for doubtful accounts		1,000	4,000
Depreciation and Software and Leasehold Amortization
Depreciation, Internally Developed Software, Amortization and Leasehold Amortization		37,810	36,042	$ 30,971
Foreign Currency Translation
Cumulative translation adjustments included in accumulated other comprehensive loss		$ 5,200	$ 3,000
Building and Building Improvements
Property and Equipment, Software and Leasehold Improvements
Estimated Useful Life		30 years
Minimum | Furniture and fixtures
Property and Equipment, Software and Leasehold Improvements
Estimated Useful Life		5 years
Minimum | Computer equipment and purchased software
Property and Equipment, Software and Leasehold Improvements
Estimated Useful Life		2 years
Minimum | Transportation equipment
Property and Equipment, Software and Leasehold Improvements
Estimated Useful Life		3 years
Minimum | Operations equipment
Property and Equipment, Software and Leasehold Improvements
Estimated Useful Life		3 years
Maximum | Furniture and fixtures
Property and Equipment, Software and Leasehold Improvements
Estimated Useful Life		7 years
Maximum | Computer equipment and purchased software
Property and Equipment, Software and Leasehold Improvements
Estimated Useful Life		5 years
Maximum | Transportation equipment
Property and Equipment, Software and Leasehold Improvements
Estimated Useful Life		7 years
Maximum | Operations equipment
Property and Equipment, Software and Leasehold Improvements
Estimated Useful Life		7 years
Minus - 10
Goodwill
Goodwill impairment charge	$ 200