Annual report pursuant to Section 13 and 15(d)

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Additional Information) (Detail)

v2.4.1.9
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Additional Information) (Detail) (USD $)
Share data in Millions, unless otherwise specified
12 Months Ended 0 Months Ended 3 Months Ended
Dec. 31, 2014
segment
Dec. 31, 2013
Dec. 31, 2012
Oct. 24, 2014
Feb. 05, 2015
Dec. 31, 2014
Significant Accounting Policies [Line Items]            
Number of reportable segments 4us-gaap_NumberOfReportableSegments          
Advertising costs from continuing operation $ 57,100,000us-gaap_AdvertisingExpense $ 57,500,000us-gaap_AdvertisingExpense $ 48,700,000us-gaap_AdvertisingExpense      
Bad debt expense from continuing operations 2,500,000us-gaap_ProvisionForDoubtfulAccounts 2,800,000us-gaap_ProvisionForDoubtfulAccounts 2,100,000us-gaap_ProvisionForDoubtfulAccounts      
Depreciation expense 71,700,000us-gaap_Depreciation 71,200,000us-gaap_Depreciation 73,900,000us-gaap_Depreciation      
Fixed assets ,Collateral 92,300,000us-gaap_PledgedAssetsSeparatelyReportedOtherAssetsPledgedAsCollateralAtFairValue 82,600,000us-gaap_PledgedAssetsSeparatelyReportedOtherAssetsPledgedAsCollateralAtFairValue       92,300,000us-gaap_PledgedAssetsSeparatelyReportedOtherAssetsPledgedAsCollateralAtFairValue
Foreign currency transaction loss 7,000,000us-gaap_ForeignCurrencyTransactionLossBeforeTax 6,800,000us-gaap_ForeignCurrencyTransactionLossBeforeTax        
Long term debt 1,527,900,000us-gaap_LongTermDebt 1,438,100,000us-gaap_LongTermDebt       1,527,900,000us-gaap_LongTermDebt
Variable interest maximum exposure to loss 15,900,000us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount         15,900,000us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount
Fair Value            
Significant Accounting Policies [Line Items]            
Fair value of interest rate swaps   6,000,000us-gaap_InterestRateDerivativeAssetsAtFairValue
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
       
Computer Software Intangible Asset | Maximum            
Significant Accounting Policies [Line Items]            
Property Plant And Equipment Useful Life 10 years          
Computer Software Intangible Asset | Minimum            
Significant Accounting Policies [Line Items]            
Property Plant And Equipment Useful Life 3 years          
Fixed Rate Debt            
Significant Accounting Policies [Line Items]            
Fair value of debt 1,300,000,000us-gaap_LongTermDebtFairValue
/ us-gaap_DebtInstrumentAxis
= efx_FixedRateDebtMember
1,200,000,000us-gaap_LongTermDebtFairValue
/ us-gaap_DebtInstrumentAxis
= efx_FixedRateDebtMember
      1,300,000,000us-gaap_LongTermDebtFairValue
/ us-gaap_DebtInstrumentAxis
= efx_FixedRateDebtMember
Long term debt 1,100,000,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= efx_FixedRateDebtMember
1,100,000,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= efx_FixedRateDebtMember
      1,100,000,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= efx_FixedRateDebtMember
Data Processing Equipment Capitalized Internal Use Software and Systems Costs | Maximum            
Significant Accounting Policies [Line Items]            
Property Plant And Equipment Useful Life 10 years          
Data Processing Equipment Capitalized Internal Use Software and Systems Costs | Computer Software Intangible Asset | Maximum            
Significant Accounting Policies [Line Items]            
Property Plant And Equipment Useful Life 3 years          
Building            
Significant Accounting Policies [Line Items]            
Property Plant And Equipment Useful Life 40 years          
Other Capitalized Property Plant and Equipment | Maximum            
Significant Accounting Policies [Line Items]            
Property Plant And Equipment Useful Life 7 years          
Other Capitalized Property Plant and Equipment | Minimum            
Significant Accounting Policies [Line Items]            
Property Plant And Equipment Useful Life 3 years          
Stock Options            
Significant Accounting Policies [Line Items]            
Antidilutive stock options excluded from computation of earnings per share 0.1us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
/ us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis
= us-gaap_EmployeeStockOptionMember
0.1us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
/ us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis
= us-gaap_EmployeeStockOptionMember
0.1us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
/ us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis
= us-gaap_EmployeeStockOptionMember
     
U.S. Information Solutions            
Significant Accounting Policies [Line Items]            
Percentage of revenue from a segment 45.00%efx_PercentageOfSegmentRevenue
/ us-gaap_StatementBusinessSegmentsAxis
= efx_USConsumerInformationSolutionsMember
         
Accelerated Share Repurchase Program            
Significant Accounting Policies [Line Items]            
Stock Repurchase Program, Authorized Amount       115,000,000us-gaap_AcceleratedShareRepurchasesSettlementPaymentOrReceipt
/ us-gaap_ShareRepurchaseProgramAxis
= efx_AcceleratedShareRepurchaseProgramMember
   
Shares issued under stock and benefit plans, net of minimum tax withholdings (in shares)       1.40us-gaap_TreasuryStockSharesAcquired
/ us-gaap_ShareRepurchaseProgramAxis
= efx_AcceleratedShareRepurchaseProgramMember
   
Treasury Stock, Holdback Provision, Percent       10.00%efx_AcceleratedShareRepurchaseProgramAdjustmentPercent
/ us-gaap_ShareRepurchaseProgramAxis
= efx_AcceleratedShareRepurchaseProgramMember
   
Accelerated Share Repurchase Program, Adjustment 11,500,000us-gaap_AcceleratedShareRepurchaseProgramAdjustment
/ us-gaap_ShareRepurchaseProgramAxis
= efx_AcceleratedShareRepurchaseProgramMember
    11,500,000us-gaap_AcceleratedShareRepurchaseProgramAdjustment
/ us-gaap_ShareRepurchaseProgramAxis
= efx_AcceleratedShareRepurchaseProgramMember
   
Stock Repurchase Program, Number of Shares Authorized to be Repurchased       3.2us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
/ us-gaap_ShareRepurchaseProgramAxis
= efx_AcceleratedShareRepurchaseProgramMember
   
Other Current Assets            
Significant Accounting Policies [Line Items]            
Restricted cash 50,800,000us-gaap_RestrictedCashAndCashEquivalents
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_OtherCurrentAssetsMember
0us-gaap_RestrictedCashAndCashEquivalents
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_OtherCurrentAssetsMember
      50,800,000us-gaap_RestrictedCashAndCashEquivalents
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_OtherCurrentAssetsMember
Other Current Liabilities            
Significant Accounting Policies [Line Items]            
Restricted cash 50,800,000us-gaap_RestrictedCashAndCashEquivalents
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_OtherCurrentLiabilitiesMember
0us-gaap_RestrictedCashAndCashEquivalents
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_OtherCurrentLiabilitiesMember
      50,800,000us-gaap_RestrictedCashAndCashEquivalents
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_OtherCurrentLiabilitiesMember
Intersegment Eliminations | International            
Significant Accounting Policies [Line Items]            
Number of operating segments 4us-gaap_NumberOfOperatingSegments
/ us-gaap_ConsolidationItemsAxis
= us-gaap_IntersegmentEliminationMember
/ us-gaap_StatementBusinessSegmentsAxis
= efx_InternationalMember
         
Subsequent Event | Accelerated Share Repurchase Program            
Significant Accounting Policies [Line Items]            
Shares issued under stock and benefit plans, net of minimum tax withholdings (in shares)         0.02us-gaap_TreasuryStockSharesAcquired
/ us-gaap_ShareRepurchaseProgramAxis
= efx_AcceleratedShareRepurchaseProgramMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
 
Interest Rate Swap            
Significant Accounting Policies [Line Items]            
Derivative, Cash Received on Hedge           $ 3,800,000us-gaap_DerivativeCashReceivedOnHedge
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember