Annual report pursuant to Section 13 and 15(d)

STOCK-BASED COMPENSATION (Additional Information) (Detail)

v2.4.1.9
STOCK-BASED COMPENSATION (Additional Information) (Detail) (USD $)
In Millions, except Share data, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
OptionPlan
Dec. 31, 2013
Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares reserved under share-based award plan 11,000,000efx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedPeriodIncrease    
Total income tax benefit recognized for stock-based compensation expense $ 13.7us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense $ 11.6us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense $ 9.8us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
Excess Tax Benefit From Share Based Compensation Operating Activities 17.7us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities 14.6us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities 1.7us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities
Stock options vesting percentage for each year of completed service 33.00%efx_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPercentage    
Stock options expiration periods 10 years    
Stock options valuation method description
We use the binomial model to calculate the fair value of stock options granted on or after January 1, 2006.
    
Minimum Percentage Of Target To Which Shares May Be Issued 0.00%efx_MinimumPercentageOfTargetToWhichSharesMayBeIssued    
Maximum Percentage Of Target To Which Shares May Be Issued 200.00%efx_MaximumPercentageOfTargetToWhichSharesMayBeIssued    
Number of active share-based award plan 1efx_NumberOfActiveShareBasedEmployeeCompensationPlans    
Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Sharebased Payment Award Options Nonvested Number Of Shares 449,790efx_SharebasedPaymentAwardOptionsNonvestedNumberOfShares
/ us-gaap_RangeAxis
= us-gaap_MinimumMember 		   
Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Sharebased Payment Award Options Nonvested Number Of Shares 899,580efx_SharebasedPaymentAwardOptionsNonvestedNumberOfShares
/ us-gaap_RangeAxis
= us-gaap_MaximumMember 		   
Stock Options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total intrinsic value of stock options exercised 42.8us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember 		43.2us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember 		38.3us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Total unrecognized compensation cost 3.1us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember 		   
Total unrecognized compensation cost, weighted-average period of recognition 1 year 6 months    
Stock Options | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock awards vesting periods 3 years    
Nonvested Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total unrecognized compensation cost 29.6us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= efx_UnvestedStockAwardsMember 		   
Total unrecognized compensation cost, weighted-average period of recognition 2 years 0 months 0 days    
Total weighted-average fair value on the vesting date 34.4us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= efx_UnvestedStockAwardsMember 		29.1us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= efx_UnvestedStockAwardsMember 		19.9us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= efx_UnvestedStockAwardsMember
Total weighted-average grant date fair value $ 17.2efx_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantDateFairValue
/ us-gaap_AwardTypeAxis
= efx_UnvestedStockAwardsMember 		$ 15.8efx_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantDateFairValue
/ us-gaap_AwardTypeAxis
= efx_UnvestedStockAwardsMember 		$ 12.8efx_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantDateFairValue
/ us-gaap_AwardTypeAxis
= efx_UnvestedStockAwardsMember
Nonvested Stock | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock awards vesting periods 1 year    
Nonvested Stock | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock awards vesting periods 3 years