Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 172.8	$ 147.8	$ 163.3	$ 131.7
Foreign currency translation:
Foreign currency translation adjustments	4.2	(116.4)	12.5	(94.0)
Reclassification adjustments recognized in net income	4.6	0.9	5.8	13.4
Foreign currency transaction and translation adjustment, net of tax	8.8	(115.5)	18.3	(80.6)
Derivative instruments:
Recognition of previously unrealized losses in net income	0.6	0.6	1.2	1.1
Income tax effect	(0.1)	(0.1)	(0.2)	(0.3)
Net unrecognized gains on derivative instruments, net of tax	0.5	0.5	1.0	0.8
Defined benefit pension and other postretirement plans:
Net actuarial gains (losses) for the period	0.7	(1.4)	0.7	(1.4)
Amortization of unrecognized losses, transition obligation and prior service cost included in net income	1.6	2.0	3.3	3.9
Settlement and curtailment losses included in net income	0.0	0.0	0.0	0.2
Other	0.6	(0.5)	0.3	(0.4)
Income tax effect	(0.1)	0.2	(0.2)	0.1
Defined benefit pension and other postretirement plans adjustment, net of tax	2.8	0.3	4.1	2.4
Other comprehensive income (loss), net of tax	12.1	(114.7)	23.4	(77.4)
TOTAL COMPREHENSIVE INCOME	184.9	33.1	186.7	54.3
Less: comprehensive income (loss) attributable to noncontrolling interests	3.6	(0.1)	2.0	(1.8)
COMPREHENSIVE INCOME ATTRIBUTABLE TO IPG	$ 181.3	$ 33.2	$ 184.7	$ 56.1