Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Income Statement [Abstract]
Revenue	$ 3,443.4	$ 3,435.0	$ 10,420.9	$ 10,433.6
Salary and service costs	2,476.1	2,461.8	7,533.9	7,609.9
Occupancy and other costs	281.0	285.5	874.2	871.0
Charges arising from the effects of the war in Ukraine	0.0	0.0	113.4	0.0
Gain on disposition of subsidiary	0.0	0.0	0.0	(50.5)
Cost of services	2,757.1	2,747.3	8,521.5	8,430.4
Selling, general and administrative expenses	86.4	95.0	294.0	269.9
Depreciation and amortization	53.9	51.1	164.8	157.9
Operating Expenses	2,897.4	2,893.4	8,980.3	8,858.2
Operating Profit	546.0	541.6	1,440.6	1,575.4
Interest Expense	52.0	50.7	154.2	184.8
Interest Income	22.9	7.0	42.2	20.1
Income Before Income Taxes and Income From Equity Method Investments	516.9	497.9	1,328.6	1,410.7
Income Tax Expense	134.7	120.0	383.3	355.1
Income From Equity Method Investments	1.1	2.2	2.6	2.1
Net Income	383.3	380.1	947.9	1,057.7
Net Income Attributed To Noncontrolling Interests	18.8	24.5	61.2	66.1
Net Income - Omnicom Group Inc.	$ 364.5	$ 355.6	$ 886.7	$ 991.6
Net Income Per Share - Omnicom Group Inc.:
Basic	$ 1.78	$ 1.66	$ 4.30	$ 4.61
Diluted	$ 1.77	$ 1.65	$ 4.27	$ 4.58