Annual report pursuant to Section 13 and 15(d)

ACQUISITIONS AND INVESTMENTS (Acquired Intangible Assets Fair Value and Weighted-Average Useful Life) (Detail)

v2.4.1.9
ACQUISITIONS AND INVESTMENTS (Acquired Intangible Assets Fair Value and Weighted-Average Useful Life) (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]    
Fair value $ 118.1us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles [1] $ 46.4us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles [1]
Weighted-average useful life 8 years 6 years 10 months 24 days
Customer relationships    
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]    
Fair value 72.1us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_CustomerRelationshipsMember 		27.6us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_CustomerRelationshipsMember
Weighted-average useful life 9 years 8 months 12 days 8 years 3 months 18 days
Acquired software and technology    
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]    
Fair value 21.7us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= efx_TechnologyAndSoftwareMember 		4.2us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= efx_TechnologyAndSoftwareMember
Weighted-average useful life 4 years 7 months 6 days 4 years 3 months 18 days
Purchased data files    
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]    
Fair value 0us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_DatabasesMember 		8.4us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_DatabasesMember
Weighted-average useful life 0 years 5 years
Non-compete agreements    
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]    
Fair value 12.8us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_NoncompeteAgreementsMember 		3.1us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_NoncompeteAgreementsMember
Weighted-average useful life 2 years 4 months 24 days 4 years
Trade names and other intangible assets    
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]    
Fair value $ 11.5us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= efx_TradenamesAndOtherMember 		$ 3.1us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= efx_TradenamesAndOtherMember
Weighted-average useful life 9 years 8 months 12 days 6 years 3 months 18 days
[1] Identifiable intangible assets are further disaggregated in the following table.