Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 383.2	$ 370.0	$ 627.1	$ 564.6
Cash flow hedge:
Amortization of loss included in interest expense	1.4	1.4	2.8	2.8
Income tax effect	(0.4)	(0.4)	(0.8)	(0.8)
Cash flow hedge, net of tax	1.0	1.0	2.0	2.0
Defined benefit pension plans and postemployment arrangements:
Amortization of prior service cost	1.0	1.1	2.1	2.1
Amortization of actuarial losses	0.2	1.4	0.4	3.0
Income tax effect	0.1	(1.1)	(0.8)	(2.4)
Defined benefit pension plans and postemployment arrangements, net of tax	1.3	1.4	1.7	2.7
Foreign currency translation adjustment	24.5	(287.2)	76.2	(259.1)
Other Comprehensive Income	26.8	(284.8)	79.9	(254.4)
TOTAL COMPREHENSIVE INCOME	410.0	85.2	707.0	310.2
Comprehensive Income Attributed To Noncontrolling Interests	13.3	2.9	29.5	24.4
COMPREHENSIVE INCOME - OMNICOM GROUP INC.	$ 396.7	$ 82.3	$ 677.5	$ 285.8