Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Earnings Per Share [Abstract]
Net income available to IPG common stockholders	$ 265.5	$ 229.6	$ 391.5	$ 389.0
Weighted-average number of common shares outstanding, Basic	385.7	393.1	385.8	393.8
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	2.0	3.7	1.8	3.7
Weighted-average number of common shares outstanding, Diluted	387.7	396.8	387.6	397.5
Earnings per share, Basic	$ 0.69	$ 0.58	$ 1.01	$ 0.99
Earnings per share, Diluted	$ 0.68	$ 0.58	$ 1.01	$ 0.98