Annual report pursuant to Section 13 and 15(d)

GOODWILL AND OTHER INTANGIBLE ASSETS (Additional Information) (Detail)

v2.4.1.9
GOODWILL AND OTHER INTANGIBLE ASSETS (Additional Information) (Detail) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 12 Months Ended
Sep. 30, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Goodwill and Intangible Assets Disclosure [Line Items]        
Goodwill   $ 2,606.8us-gaap_Goodwill $ 2,395.1us-gaap_Goodwill [1] $ 2,290.4us-gaap_Goodwill [1]
Amortization expense related to purchased intangible assets   129.9us-gaap_AmortizationOfIntangibleAssets 118.4us-gaap_AmortizationOfIntangibleAssets 86.1us-gaap_AmortizationOfIntangibleAssets
Intangible assests, gross   1,475.4us-gaap_FiniteLivedIntangibleAssetsGross 1,397.2us-gaap_FiniteLivedIntangibleAssetsGross  
Increase in goodwill 85.5us-gaap_GoodwillPeriodIncreaseDecrease      
Reduction in indefinite-lived intangible 158.8us-gaap_IndefiniteLivedIntangibleAssetsPeriodIncreaseDecrease      
Reacquired Rights        
Goodwill and Intangible Assets Disclosure [Line Items]        
Intangible assests, gross 73.3us-gaap_FiniteLivedIntangibleAssetsGross
/ us-gaap_RegulatoryAssetAxis
= efx_ReacquiredsRightsMember 		     
Useful Life 5 years 7 months 6 days      
U.S. Information Solutions        
Goodwill and Intangible Assets Disclosure [Line Items]        
Goodwill   1,120.6us-gaap_Goodwill
/ us-gaap_StatementBusinessSegmentsAxis
= efx_USConsumerInformationSolutionsMember 		1,054.2us-gaap_Goodwill
/ us-gaap_StatementBusinessSegmentsAxis
= efx_USConsumerInformationSolutionsMember 		[1] 969.4us-gaap_Goodwill
/ us-gaap_StatementBusinessSegmentsAxis
= efx_USConsumerInformationSolutionsMember 		[1]
International        
Goodwill and Intangible Assets Disclosure [Line Items]        
Goodwill   561.9us-gaap_Goodwill
/ us-gaap_StatementBusinessSegmentsAxis
= efx_InternationalMember 		416.5us-gaap_Goodwill
/ us-gaap_StatementBusinessSegmentsAxis
= efx_InternationalMember 		[1] 385.2us-gaap_Goodwill
/ us-gaap_StatementBusinessSegmentsAxis
= efx_InternationalMember 		[1]
Intersegment Eliminations | U.S. Information Solutions        
Goodwill and Intangible Assets Disclosure [Line Items]        
Goodwill     21.7us-gaap_Goodwill
/ us-gaap_ConsolidationItemsAxis
= us-gaap_IntersegmentEliminationMember
/ us-gaap_StatementBusinessSegmentsAxis
= efx_USConsumerInformationSolutionsMember 		21.7us-gaap_Goodwill
/ us-gaap_ConsolidationItemsAxis
= us-gaap_IntersegmentEliminationMember
/ us-gaap_StatementBusinessSegmentsAxis
= efx_USConsumerInformationSolutionsMember
Intersegment Eliminations | International        
Goodwill and Intangible Assets Disclosure [Line Items]        
Goodwill     $ 15.5us-gaap_Goodwill
/ us-gaap_ConsolidationItemsAxis
= us-gaap_IntersegmentEliminationMember
/ us-gaap_StatementBusinessSegmentsAxis
= efx_InternationalMember 		$ 15.9us-gaap_Goodwill
/ us-gaap_ConsolidationItemsAxis
= us-gaap_IntersegmentEliminationMember
/ us-gaap_StatementBusinessSegmentsAxis
= efx_InternationalMember
[1] The December 31, 2013 and 2012 balances have been recast to reflect the new organizational structure. As of December 31, 2013, the USIS and International goodwill include $21.7 million and $15.5 million of goodwill, respectively, from the legacy NACS segment. As of December 31, 2012, the USIS and International goodwill include $21.7 million and $15.9 million of goodwill, respectively, from the legacy NACS segment