Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Statement of Comprehensive Income [Abstract]
NET INCOME (LOSS)	$ (85.3)	$ 113.6
Foreign currency translation:
Foreign currency translation adjustments	64.8	(52.3)
Reclassification adjustments recognized in net income	20.3	0.0
Foreign currency transaction and translation adjustment, net of tax	85.1	(52.3)
Derivative Instrument:
Recognition of previously unrealized gain in net income	(1.0)	(0.9)
Income tax effect	0.3	0.2
Net unrecognized gains on derivative instruments, net of tax	(0.7)	(0.7)
Defined benefit pension and other postretirement plans:
Net actuarial gains for the period	(0.2)	0.8
Amortization of unrecognized losses, transition obligation and prior service cost included in net income	2.2	1.9
Other	(0.2)	0.1
Income tax effect	(0.5)	(0.5)
Defined benefit pension and other postretirement plans adjustment, net of tax	1.3	2.3
Other comprehensive loss, net of tax	85.7	(50.7)
TOTAL COMPREHENSIVE INCOME	0.4	62.9
Less: comprehensive income attributable to noncontrolling interests	0.3	2.0
COMPREHENSIVE INCOME ATTRIBUTABLE TO IPG	$ 0.1	$ 60.9