Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 1,473.2	$ 1,403.8	$ 1,507.6
Cash flow hedge:
Amortization of loss included in interest expense	5.6	5.6	5.6
Income tax effect	(1.6)	(1.6)	(1.6)
Other comprehensive income (loss), Cash flow hedge	4.0	4.0	4.0
Defined benefit pension plans and postemployment arrangements:
Unrecognized actuarial gains (losses) and prior service cost for the period	(6.8)	58.4	28.3
Amortization of prior service cost and actuarial (gains) losses	4.8	10.7	18.1
Income tax effect	0.6	(20.0)	(13.6)
Other comprehensive income (loss), Defined benefit pension plans and postemployment arrangements	(1.4)	49.1	32.8
Foreign currency translation adjustment	98.9	(255.2)	(92.2)
Other Comprehensive Income (Loss)	101.5	(202.1)	(55.4)
Comprehensive Income	1,574.7	1,201.7	1,452.2
Comprehensive Income Attributed To Noncontrolling Interests	83.0	70.8	82.9
Comprehensive Income - Omnicom Group Inc.	$ 1,491.7	$ 1,130.9	$ 1,369.3