Annual report pursuant to Section 13 and 15(d)

COMMITMENTS AND CONTINGENCIES (Additional Information) (Details)

v3.8.0.1
COMMITMENTS AND CONTINGENCIES (Additional Information) (Details)
customer in Thousands
 6 Months Ended 12 Months Ended
Dec. 31, 2017
USD ($)
office
lawsuit
claim
Dec. 31, 2017
USD ($)
customer
office
lawsuit
claim
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Commitments and Contingencies Disclosure [Line Items]        
Rental expense for operating leases   $ 34,500,000 $ 29,100,000 $ 24,200,000
Cash paid for data processing, outsourcing services and other agreements   $ 40,000,000 $ 45,000,000 $ 50,000,000
Qualifying termination period, continuation of benefits for executives   3 years    
Qualifying termination period, continuation of benefits for executives, automatic renewal   3 years    
Change in control event, voting stock acquired (or more)   20.00%    
Conditional payment for unrecognized severance benefit for key executives   $ 45,900,000    
Assumed tax on expected payment for unrecognized severance benefit for key executives $ 10,300,000 $ 10,300,000    
Conditional payout percentage of target award   100.00%    
Maximum potential future payments required to make under guarantees 0 $ 0    
Change in control event, minimum common stock received   66.67%    
Letter of Credit        
Commitments and Contingencies Disclosure [Line Items]        
Notional amount 0 $ 0    
Minimum        
Commitments and Contingencies Disclosure [Line Items]        
Benefit continuation period   2 years    
Maximum        
Commitments and Contingencies Disclosure [Line Items]        
Benefit continuation period   3 years    
Performance Bonds        
Commitments and Contingencies Disclosure [Line Items]        
Notional amount 0 $ 0    
Data Processing, Outsourcing Services And Other Agreements | Minimum        
Commitments and Contingencies Disclosure [Line Items]        
Data processing, outsourcing services and other agreements, expiration year   2018    
Data processing, outsourcing services and other agreements, estimated aggregate contractual obligation 125,000,000 $ 125,000,000    
Non cancelable contractual obligations within any annual period 85,000,000 $ 85,000,000    
Data Processing, Outsourcing Services And Other Agreements | Maximum        
Commitments and Contingencies Disclosure [Line Items]        
Data processing, outsourcing services and other agreements, expiration year   2022    
IBM Operations Support Services Agreement        
Commitments and Contingencies Disclosure [Line Items]        
Expected future year's minimum contractual obligation 48,000,000 $ 48,000,000    
Expected future year's minimum contractual obligation within any annual period 24,000,000 $ 24,000,000    
Cybersecurity Incident        
Commitments and Contingencies Disclosure [Line Items]        
Number of customers impacted | customer   145,500    
Loss contingency, loss in period $ 164,000,000      
Number of state Attorneys General offices in cooperation with | office 49 49    
Number of putative shareholder derivative lawsuits | lawsuit 4 4    
Number of claims for violations of certain federal securities laws | claim 3 3    
Insurance settlements receivable $ 35,000,000 $ 35,000,000    
Proceeds from insurance settlement $ 15,000,000 $ 15,000,000    
Cybersecurity Incident | U.S.        
Commitments and Contingencies Disclosure [Line Items]        
Number of customers, personal information accessed | customer   182    
Number of customers, name and partial driver's license information stolen | customer   2,400    
Cybersecurity Incident | United States and Canada        
Commitments and Contingencies Disclosure [Line Items]        
Number of customers, credit card information accessed | customer   209    
Cybersecurity Incident | Canada        
Commitments and Contingencies Disclosure [Line Items]        
Number of customers, personal information accessed | customer   19    
Cybersecurity Incident | U.K.        
Commitments and Contingencies Disclosure [Line Items]        
Number of customers, personal information accessed | customer   860    
Cybersecurity Incident | GEORGIA        
Commitments and Contingencies Disclosure [Line Items]        
Number of putative class actions | lawsuit 4 4    
Cybersecurity Incident, Investigation, Remediation, Legal, And Other Professional Services        
Commitments and Contingencies Disclosure [Line Items]        
Loss contingency, loss in period   $ 113,300,000    
Insurance coverage amount   125,000,000    
Insurance coverage deductible   7,500,000.0    
Cybersecurity Incident, Investigation, Remediation, Legal, And Other Professional Services | Cost of services        
Commitments and Contingencies Disclosure [Line Items]        
Loss contingency, loss in period   14,200,000    
Cybersecurity Incident, Investigation, Remediation, Legal, And Other Professional Services | Selling, general and administrative expenses        
Commitments and Contingencies Disclosure [Line Items]        
Loss contingency, loss in period   99,100,000    
Cybersecurity Incident, Free Credit File Monitoring And Identity Theft Protection Offering        
Commitments and Contingencies Disclosure [Line Items]        
Loss contingency, loss in period   $ 50,700,000