Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Earnings Per Share [Abstract]
Net income available to IPG common stockholders	$ 214.5	$ 265.5	$ 324.9	$ 391.5
Weighted-average number of common shares outstanding, Basic	376.3	385.7	377.4	385.8
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	2.4	2.0	2.3	1.8
Weighted-average number of common shares outstanding, Diluted	378.7	387.7	379.7	387.6
Earnings per share, Basic	$ 0.57	$ 0.69	$ 0.86	$ 1.01
Earnings per share, Diluted	$ 0.57	$ 0.68	$ 0.86	$ 1.01