Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
Net revenue	$ 9,187.6	$ 9,400.6	$ 9,449.4
Billable expenses	1,504.1	1,488.7	1,478.4
Total revenue	10,691.7	10,889.3	10,927.8
OPERATING EXPENSES:
Salaries and related expenses	6,024.8	6,243.9	6,258.3
Office and other direct expenses	1,343.1	1,342.5	1,346.4
Billable expense	1,504.1	1,488.7	1,478.4
Cost of services	8,872.0	9,075.1	9,083.1
Selling, General and Administrative Expense	130.5	67.2	87.1
Depreciation and amortization	258.9	264.3	274.0
Goodwill, Impairment Loss	232.1	0.0	0.0
Restructuring Charges	(5.0)	0.1	102.4
Total operating expenses	9,488.5	9,406.7	9,546.6
OPERATING INCOME	1,203.2	1,482.6	1,381.2
EXPENSES AND OTHER INCOME:
Interest expense	(229.9)	(225.6)	(167.9)
Interest income	151.7	140.8	56.6
Other (expense) income, net	(75.9)	10.2	(1.0)
Total (expenses) and other income	(154.1)	(74.6)	(112.3)
Income before income taxes	1,049.1	1,408.0	1,268.9
Provision for income taxes	333.9	291.2	318.4
Income of consolidated companies	715.2	1,116.8	950.5
Equity in net income of unconsolidated affiliates	0.5	1.3	5.6
NET INCOME	715.7	1,118.1	956.1
Net Income Attributable to Nonredeemable Noncontrolling Interest	(26.2)	(19.7)	(18.1)
Net Income Attributable to Parent	$ 689.5	$ 1,098.4	$ 938.0
Earnings per share available to IPG common stockholders:
Earnings per share, Basic	$ 1.84	$ 2.86	$ 2.40
Earnings per share, Diluted	$ 1.83	$ 2.85	$ 2.37
Weighted-average number of common shares outstanding:
Weighted-average number of common shares outstanding, Basic	375.2	384.1	391.5
Weighted-average number of common shares outstanding, Diluted	377.7	385.9	395.1