Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Statement [Abstract]
Revenue	$ 3,567.2	$ 3,571.6	$ 6,977.5	$ 6,998.6
Salary and service costs	2,566.0	2,603.1	5,057.8	5,148.1
Occupancy and other costs	293.0	293.9	593.2	585.5
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	(50.5)	0.0	(50.5)
Cost of services	2,859.0	2,846.5	5,764.4	5,683.1
Selling, general and administrative expenses	110.9	103.2	207.6	174.9
Depreciation and amortization	55.7	53.5	110.9	106.8
Operating Expenses	3,025.6	3,003.2	6,082.9	5,964.8
Operating Profit	541.6	568.4	894.6	1,033.8
Interest Expense	51.2	80.3	102.2	134.1
Interest Income	11.1	6.8	19.3	13.1
Income Before Income Taxes and Income (Loss) From Equity Method Investments	501.5	494.9	811.7	912.8
Income Tax Expense	133.1	123.2	248.6	235.2
Income (Loss) From Equity Method Investments	1.6	(0.1)	1.5	(0.1)
Net Income	370.0	371.6	564.6	677.5
Net Income Attributed To Noncontrolling Interests	21.6	23.4	42.4	41.5
Net Income - Omnicom Group Inc.	$ 348.4	$ 348.2	$ 522.2	$ 636.0
Net Income Per Share - Omnicom Group Inc.:
Basic	$ 1.70	$ 1.62	$ 2.53	$ 2.95
Diluted	$ 1.68	$ 1.60	$ 2.51	$ 2.93