ACCUMULATED OTHER COMPREHENSIVE LOSS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Unrecognized actuarial losses and prior service cost related to pension and other postretirement benefit plans, accumulated tax	$ 95.6	$ 150.6	$ 138.2
Cash flow hedging transactions, tax	$ 0.7	$ 0.9	$ 1.0

The tax effect from the total of net (gain) loss, prior service cost (credit), and transition assets (obligations), as well as minimum pension liability if still remaining, included in accumulated other comprehensive income associated with a defined benefit pension or other postretirement plan(s) because they have yet to be recognized as components of net periodic benefit cost.

No definition available.

Name:	efx_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansTax
Namespace Prefix:	efx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant