Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Net revenue	$ 9,400.6	$ 9,449.4	$ 9,107.9
Billable expenses	1,488.7	1,478.4	1,132.8
Total revenue	10,889.3	10,927.8	10,240.7
OPERATING EXPENSES:
Salaries and related expenses	6,243.9	6,258.3	5,975.4
Office and other direct expenses	1,342.5	1,346.4	1,279.6
Billable expense	1,488.7	1,478.4	1,132.8
Cost of services	9,075.1	9,083.1	8,387.8
Selling, General and Administrative Expense	67.2	87.1	122.3
Depreciation and amortization	264.3	274.0	283.8
Restructuring Charges	0.1	102.4	10.6
Total operating expenses	9,406.7	9,546.6	8,804.5
OPERATING INCOME	1,482.6	1,381.2	1,436.2
EXPENSES AND OTHER INCOME:
Interest expense	(225.6)	(167.9)	(170.6)
Interest income	140.8	56.6	27.2
Other income (expense), net	10.2	(1.0)	(70.7)
Total (expenses) and other income	(74.6)	(112.3)	(214.1)
Income before income taxes	1,408.0	1,268.9	1,222.1
Provision for income taxes	291.2	318.4	251.8
Income of consolidated companies	1,116.8	950.5	970.3
Equity in net income of unconsolidated affiliates	1.3	5.6	2.5
NET INCOME	1,118.1	956.1	972.8
Net Income Attributable to Nonredeemable Noncontrolling Interest	(19.7)	(18.1)	(20.0)
Net Income Attributable to Parent	$ 1,098.4	$ 938.0	$ 952.8
Earnings per share available to IPG common stockholders:
Earnings per share, Basic	$ 2.86	$ 2.40	$ 2.42
Earnings per share, Diluted	$ 2.85	$ 2.37	$ 2.39
Weighted-average number of common shares outstanding:
Weighted-average number of common shares outstanding, Basic	384.1	391.5	393.0
Weighted-average number of common shares outstanding, Diluted	385.9	395.1	398.4