Quarterly report pursuant to Section 13 or 15(d)

GOODWILL AND INTANGIBLE ASSETS - Purchased Intangible Assets (Details)

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GOODWILL AND INTANGIBLE ASSETS - Purchased Intangible Assets (Details) - USD ($)
$ in Millions
Sep. 30, 2018
Dec. 31, 2017
Acquired Finite-Lived Intangible Assets [Line Items]    
Gross $ 1,875.7 $ 2,000.1
Accumulated Amortization (742.9) (753.1)
Net 1,132.8 1,247.0
Purchased data files    
Acquired Finite-Lived Intangible Assets [Line Items]    
Gross 918.2 955.7
Accumulated Amortization (291.8) (262.2)
Net 626.4 693.5
Acquired software and technology    
Acquired Finite-Lived Intangible Assets [Line Items]    
Gross 118.8 142.3
Accumulated Amortization (65.9) (66.6)
Net 52.9 75.7
Customer relationships    
Acquired Finite-Lived Intangible Assets [Line Items]    
Gross 694.9 772.4
Accumulated Amortization (286.3) (326.7)
Net 408.6 445.7
Reacquired rights    
Acquired Finite-Lived Intangible Assets [Line Items]    
Gross 73.3 73.3
Accumulated Amortization (73.3) (65.6)
Net 0.0 7.7
Proprietary database    
Acquired Finite-Lived Intangible Assets [Line Items]    
Gross 46.3 22.1
Accumulated Amortization (11.1) (8.7)
Net 35.2 13.4
Non-compete agreements    
Acquired Finite-Lived Intangible Assets [Line Items]    
Gross 4.9 14.1
Accumulated Amortization (3.2) (12.7)
Net 1.7 1.4
Trade names and other intangible assets    
Acquired Finite-Lived Intangible Assets [Line Items]    
Gross 19.3 20.2
Accumulated Amortization (11.3) (10.6)
Net $ 8.0 $ 9.6