Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Income Statement [Abstract]
Revenue	$ 3,690.4	$ 3,630.5
Salary and service costs	2,746.3	2,692.6
Occupancy and other costs	314.6	314.1
Cost of services	3,060.9	3,006.7
Selling, general and administrative expenses	117.9	85.3
Depreciation and amortization	59.0	59.6
Total Operating Expenses	3,237.8	3,151.6
Operating Income	452.6	478.9
Interest Expense	59.1	53.8
Interest Income	29.7	27.0
Income Before Income Taxes and Income From Equity Method Investments	423.2	452.1
Income Tax Expense	120.7	116.0
Income From Equity Method Investments	0.9	0.9
Net Income	303.4	337.0
Net Income Attributed To Noncontrolling Interests	15.7	18.4
Net Income - Omnicom Group Inc.	$ 287.7	$ 318.6
Net Income Per Share - Omnicom Group Inc.:
Basic	$ 1.46	$ 1.61
Diluted	$ 1.45	$ 1.59
Weighted Average Shares:
Basic	196.7	197.9
Diluted	198.3	200.1