Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 715.7	$ 1,118.1	$ 956.1
Foreign Currency Translation:
Foreign currency translation adjustments	(153.4)	59.3	(131.8)
Reclassification adjustments recognized in net income	0.2	0.5	4.3
Foreign currency translation, net of tax	(153.2)	59.8	(127.5)
Derivatives instruments:
Changes in fair value of derivative instruments	0.0	0.6	17.5
Recognition of previously unrealized gains included in net income	(3.8)	(2.6)	(1.4)
Income tax effect	1.0	0.5	(4.0)
Derivative instruments, net of tax	(2.8)	(1.5)	12.1
Defined benefit pension and other postretirement plans:
Net actuarial (losses) gains for the period	(24.1)	(17.4)	2.4
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax	7.5	6.8	6.3
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	(0.3)	(0.3)	0.0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Other, before Tax	1.1	(2.1)	4.8
Income tax effect	3.9	2.0	0.8
Defined benefit pension and other postretirement plans, net of tax	(11.9)	(11.0)	14.3
Other comprehensive (loss) income, net of tax	(167.9)	47.3	(101.1)
Total comprehensive income	547.8	1,165.4	855.0
Less: comprehensive income attributable to noncontrolling interests	24.7	19.5	16.5
Comprehensive Income Attributable to IPG	$ 523.1	$ 1,145.9	$ 838.5